Devices for urea electrolysis and methods of using same

ABSTRACT

The present disclosure provides devices and methods of using same for cleansing a solution (e.g., a salt solution) of urea via electrooxidation, and more specifically to cleansing a renal therapy solution/dialysis solution of urea via electrooxidation so that the renal therapy solution/dialysis solution can be used or reused for treatment of a patient. In an embodiment, a device for the removal of urea from a fluid having urea to produce a cleansed fluid includes a urea decomposition unit and an electrodialysis unit.

PRIORITY CLAIM

The present application claims priority to U.S. Provisional ApplicationNo. 62/273,863, filed Dec. 31, 2015, entitled, “Devices for UreaElectrolysis and Methods of Using Same.

CROSS-REFERENCE TO RELATED APPLICATION

The present application shares much of the same written description anddrawings with commonly owned and concurrently filed U.S. patentapplication Ser. No. ______, Attorney Docket No. P6851 US01 BX2016T00475(3712044-04522), entitled “Devices for Urea Electrolysis withCombination Electrodialysis and Urea Oxidation Cell and Methods of UsingSame”, which also claims priority to U.S. Provisional Application No.62/273,863.

BACKGROUND

Due to disease or insult or other causes, the renal system can fail. Inrenal failure of any cause, there are several physiologicalderangements. The balance of water, ions (e.g., Na⁺, K⁺, Cl⁻, Ca²⁺, PO₄³⁻, Mg²⁺, SO₄ ²⁻) and the excretion of daily metabolic load of fixedhydrogen ions is no longer possible in renal failure. Further, duringrenal failure, toxic end products of nitrogen metabolism including, forexample, urea, creatinine, uric acid, and others can accumulate in bloodand tissues.

Several types of dialysis have been devised (e.g., peritoneal dialysis,hemodialysis, hemofiltration, and hemodiafiltration) for the removal oftoxic end products of nitrogen metabolism from blood. These types ofdialysis rely on diffusion of urea across a membrane and/or enzymaticdegradation of urea. However, degradation of urea is problematic in thatit produces toxic end products such as ammonium that must be removed andor trapped to ensure that they are not returned to a patient. Oftensorbents are employed during dialysis to bind such toxic end products.These sorbents are expensive and add bulk to a dialysis system makingthem less suitable to being used in portable or wearable applications.Therefore, there is a need for dialysis systems that can remove ureafrom blood without generating toxic end products.

SUMMARY

The present disclosure provides devices and methods of using same forcleansing a solution (e.g., a salt solution) comprising urea viaelectrooxidation. In a first general embodiment, which may be used incombination with any other embodiment described herein unless specifiedotherwise, a device for the removal of urea from a fluid having urea toproduce a cleansed fluid, the device comprises a urea decomposition unitcomprising an inlet for entry of the fluid having urea and an outlet forremoval of the cleansed fluid, and one or more sets of electrodes havingan anode and a cathode with an electrocatalytic surface fordecomposition of urea via electrooxidation; and an electrodialysis unitcomprising a set of electrodes having an anode and a cathode forseparation of a salt solution via electrodialysis, where the saltsolution is separated into an acid stream and a basic stream, wherein atleast one of (i) the basic stream of the electrodialysis unit is placedin fluid communication with the inlet of the urea decomposition unit,(ii) the acid stream from the electrodialysis unit is placed in fluidcommunication with the outlet of the urea decomposition unit or (iii)the acid stream is circulated through the electrodialysis unit.

In a second general embodiment, which may be used in combination withany other embodiment described herein unless specified otherwise, theelectrodialysis unit comprises a first cell comprising a first bipolarmembrane, a first ion exchange membrane, and a second ion exchangemembrane, wherein the first ion exchange membrane is positioned next toone side of the first bipolar membrane and the second ion exchangemembrane is positioned next to an opposite side of the first bipolarmembrane, thereby forming (i) a first compartment between the firstbipolar membrane and the first ion exchange membrane and (ii) a secondcompartment between the first bipolar membrane and the second ionexchange membrane.

In a third general embodiment, which may be used with the secondembodiment in combination with any other embodiment described hereinunless specified otherwise, the first ion exchange membrane is an anionexchange membrane or a cation exchange membrane.

In a fourth general embodiment, which may be used with the secondembodiment in combination with any other embodiment described hereinunless specified otherwise, the second ion exchange membrane is an anionexchange membrane or a cation exchange membrane.

In a fifth general embodiment, which may be used with the secondembodiment in combination with any other embodiment described hereinunless specified otherwise, the electrodialysis unit further comprises asecond cell including a second bipolar membrane and a third ion exchangemembrane, wherein the second cell is positioned next to the first cell,and wherein the second bipolar membrane is positioned between the secondion exchange membrane of the first cell and the third ion exchangemembrane, thereby forming a third compartment between the second bipolarmembrane and the third ion exchange membrane.

In a sixth general embodiment, which may be used with the fifthembodiment in combination with any other embodiment described hereinunless specified otherwise, the first, second, and third ion exchangemembranes are cation exchange membranes, or the first, second, and thirdion exchange membranes are anion exchange membranes.

In a seventh general embodiment, which may be used in combination withany other embodiment described herein unless specified otherwise, theelectrodialysis unit comprises a cell including a first bipolarmembrane, a second bipolar membrane, a first ion exchange membrane, anda second ion exchange membrane, wherein the first ion exchange membraneand the second ion exchange membrane are positioned between the firstbipolar membrane and the second bipolar membrane, thereby forming afirst compartment between the first bipolar membrane and the first ionexchange membrane, a second compartment between the first ion exchangemembrane and the second ion exchange membrane, and a third compartmentbetween the second ion exchange membrane and the second bipolarmembrane.

In an eighth general embodiment, which may be used with the seventhembodiment in combination with any other embodiment described hereinunless specified otherwise, the first ion exchange membrane is a cationexchange membrane and the second ion exchange membrane is an anionexchange membrane.

In a ninth general embodiment, which may be used in combination with anyother embodiment described herein unless specified otherwise, a powersource in the urea decomposition unit provides the electrodes with anelectrical charge to activate the electrocatalytic surface of theelectrodes.

In a tenth general embodiment, which may be used in combination with anyother embodiment described herein unless specified otherwise, a powersource in the electrodialysis unit provides the electrodes with anelectrical charge to split water in a bipolar membrane into H⁺ and OH⁻.

In an eleventh general embodiment, which may be used in combination withany other embodiment described herein unless specified otherwise, theelectrodialysis unit separates the salt solution via bipolar membraneelectrodialysis.

In a twelfth general embodiment, which may be used in combination withany other embodiment described herein unless specified otherwise, thebasic stream of the electrodialysis unit is in fluid communication withthe inlet of the urea decomposition unit and the acid stream from theelectrodialysis unit is in fluid communication with the outlet of theurea decomposition unit.

In a thirteenth general embodiment, which may be used in combinationwith any other embodiment described herein unless specified otherwise,the salt solution is a dialysis fluid.

In a fourteenth general embodiment, which may be used with thethirteenth embodiment in combination with any other embodiment describedherein unless specified otherwise, the dialysis fluid includes one ormore salts selected from the group consisting of: a sodium salt, amagnesium salt, a calcium salt, lactate, carbonate, acetate, citrate, orphosphate.

In a fifteenth general embodiment, which may be used in combination withany other embodiment described herein unless specified otherwise, thedevice includes a tank for the salt solution.

In a sixteenth general embodiment, which may be used in combination withany other embodiment described herein unless specified otherwise, thebasic stream includes NaOH.

In a seventeenth general embodiment, which may be used in combinationwith any other embodiment described herein unless specified otherwise,the acid stream includes HCl.

In an eighteenth general embodiment, which may be used in combinationwith any other embodiment described herein unless specified otherwise,the anodes in the urea decomposition unit comprise a transition metaland/or mixtures thereof and/or alloys thereof.

In a nineteenth general embodiment, which may be used with theeighteenth embodiment in combination with any other embodiment describedherein unless specified otherwise, the transition metal is cobalt,copper, iron, nickel, platinum, palladium, iridium, ruthenium, orrhodium.

In a twentieth general embodiment, which may be used with the eighteenthembodiment in combination with any other embodiment described hereinunless specified otherwise, the anodes in the urea decomposition unitcomprise nickel, nickel oxide, nickel hydroxide or nickel oxidehydroxide (NiOOH).

In a twenty-first general embodiment, which may be used in combinationwith any other embodiment described herein unless specified otherwise,the urea decomposition unit includes an alkaline polymeric gel.

In a twenty-second general embodiment, which may be used in combinationwith any other embodiment described herein unless specified otherwise,the fluid having urea is a dialysis fluid contaminated with urea.

In a twenty-third general embodiment, which may be used in combinationwith any other embodiment described herein unless specified otherwise, avoltage difference applied across the cathodes and the anodes in theurea decomposition unit is sufficient to produce nitrogen gas, carbondioxide gas, and water.

In a twenty-fourth general embodiment, which may be used in combinationwith any other embodiment described herein unless specified otherwise, arenal replacement therapy system includes a dialysis fluid circuit. Thedialysis fluid circuit comprises a device for the removal of urea from adialysis fluid having urea to produce a cleansed dialysis fluid. Thedevice includes a urea decomposition unit comprising an inlet for entryof the dialysis fluid having urea and an outlet for removal of thecleansed dialysis fluid, and a set of electrodes having an anode and acathode with an electrocatalytic surface for decomposition of urea viaelectrooxidation; and an electrodialysis unit comprising a set ofelectrodes having an anode and a cathode for separation of a saltsolution via electrodialysis, where the salt solution is separated intoan acid stream and a basic stream, wherein at least one of (i) the basicstream of the electrodialysis unit is placed in fluid communication withthe inlet of the urea decomposition unit, (ii) the acid stream from theelectrodialysis unit is placed in fluid communication with the outlet ofthe urea decomposition unit, or (iii) the acid stream is circulatedthrough the electrodialysis unit.

In a twenty-fifth general embodiment, which may be used with thetwenty-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the cleansed dialysis fluidrecirculates through the dialysis fluid circuit.

In a twenty-sixth general embodiment, which may be used with thetwenty-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitcomprises a first cell including a first bipolar membrane, a first ionexchange membrane, and a second ion exchange membrane, wherein the firstion exchange membrane is positioned next to one side of the firstbipolar membrane and the second ion exchange membrane is positioned nextto an opposite side of the first bipolar membrane, thereby forming afirst compartment between the first bipolar membrane and the first ionexchange membrane and a second compartment between the first bipolarmembrane and the second ion exchange membrane.

In a twenty-seventh general embodiment, which may be used with thetwenty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the first ion exchangemembrane is an anion exchange membrane or a cation exchange membrane.

In a twenty-eighth general embodiment, which may be used with thetwenty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the second ion exchangemembrane is an anion exchange membrane or a cation exchange membrane.

In a twenty-ninth general embodiment, which may be used with thetwenty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitfurther comprises a second cell including a second bipolar membrane anda third ion exchange membrane, wherein the second cell is positionednext to the first cell, and wherein the second bipolar membrane ispositioned between the second ion exchange membrane of the first celland the third ion exchange membrane, thereby forming a third compartmentbetween the second bipolar membrane and the third ion exchange membrane.

In a thirtieth general embodiment, which may be used with thetwenty-ninth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the first, second, andthird ion exchange membranes are cation exchange membranes or the first,second, and third ion exchange membranes are anion exchange membranes.

In a thirty-first general embodiment, which may be used with thetwenty-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitcomprises a cell including a first bipolar membrane, a second bipolarmembrane, a first ion exchange membrane, and a second ion exchangemembrane, wherein the first ion exchange membrane and the second ionexchange membrane are positioned between the first bipolar membrane andthe second bipolar membrane, thereby forming a first compartment betweenthe first bipolar membrane and the first ion exchange membrane, a secondcompartment between the first ion exchange membrane and the second ionexchange membrane, and a third compartment between the second ionexchange membrane and the second bipolar membrane.

In a thirty-second general embodiment, which may be used with thethirty-first embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the first ion exchangemembrane is a cation exchange membrane and the second ion exchangemembrane is an anion exchange membrane.

In a thirty-third general embodiment, which may be used with thetwenty-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, a power source in the ureadecomposition unit provides the electrodes with an electrical charge toactivate the electrocatalytic surface of the electrodes.

In a thirty-fourth general embodiment, which may be used with thetwenty-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, a power source in theelectrodialysis unit provides the electrodes with an electrical chargeto split water in a bipolar membrane into H⁺ and OH⁻.

In a thirty-fifth general embodiment, which may be used with thetwenty-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitseparates the salt solution via bipolar membrane electrodialysis.

In a thirty-sixth general embodiment, which may be used with thetwenty-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the salt solution is adialysis fluid.

In a thirty-seventh general embodiment, which may be used with thethirty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the dialysis fluid includesone or more salts selected from the group consisting of: a sodium salt,a magnesium salt, a calcium salt, lactate, carbonate, acetate, citrate,or phosphate.

In a thirty-eighth general embodiment, which may be used with thetwenty-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the device includes a tankfor the salt solution.

In a thirty-ninth general embodiment, which may be used with thetwenty-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the basic stream includesNaOH.

In a fortieth general embodiment, which may be used with thetwenty-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the acid stream includesHCl.

In a forty-first general embodiment, which may be used with thetwenty-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the anodes in the ureadecomposition unit comprise a transition metal and/or mixtures thereofand/or alloys thereof.

In a forty-second general embodiment, which may be used with theforty-first embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the transition metal iscobalt, copper, iron, nickel, platinum, palladium, iridium, ruthenium,or rhodium.

In a forty-third general embodiment, which may be used with theforty-first embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the anodes in the ureadecomposition unit comprise nickel, nickel oxide, nickel hydroxide ornickel oxide hydroxide (NiOOH).

In a forty-fourth general embodiment, which may be used with thetwenty-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the urea decomposition unitincludes an alkaline polymeric gel.

In a forty-fifth general embodiment, which may be used with thetwenty-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, a voltage differenceapplied across the cathodes and the anodes in the urea decompositionunit is sufficient to produce nitrogen gas, carbon dioxide gas, andwater.

In a forty-sixth general embodiment, which may be used with any otherembodiment described herein unless specified otherwise, a method ofperforming a renal replacement therapy includes passing a dialysis fluidhaving urea through a device. The device includes: a urea decompositionunit comprising an inlet for entry of the used dialysis fluid havingurea and an outlet for removal of the cleansed dialysis fluid, and a setof electrodes having an anode and a cathode with an electrocatalyticsurface for decomposition of urea via electrooxidation; and anelectrodialysis unit comprising a set of electrodes having an anode anda cathode with an electrocatalytic surface for separation of a saltsolution via electrodialysis, where the salt solution is separated intoan acid stream and a basic stream, wherein at least one of (i) the basicstream of the electrodialysis unit is placed in fluid communication withthe inlet of the urea decomposition unit, (ii) the acid stream from theelectrodialysis unit is in fluid communication with the outlet of theurea decomposition unit, or (iii) the acid stream is circulated throughthe electrodialysis unit, and wherein the dialysis fluid exiting theoutlet of the urea decomposition unit is cleansed dialysis fluid.

In a forty-seventh general embodiment, which may be used with theforty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitcomprises a first cell including a first bipolar membrane, a first ionexchange membrane, and a second ion exchange membrane, wherein the firstion exchange membrane is positioned next to one side of the firstbipolar membrane and the second ion exchange membrane is positioned nextto an opposite side of the first bipolar membrane, thereby forming afirst compartment between the first bipolar membrane and the first ionexchange membrane and a second compartment between the first bipolarmembrane and the second ion exchange membrane.

In a forty-eighth general embodiment, which may be used with theforty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the first ion exchangemembrane is an anion exchange membrane or a cation exchange membrane.

In a forty-ninth general embodiment, which may be used with theforty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the second ion exchangemembrane is an anion exchange membrane or a cation exchange membrane.

In a fiftieth general embodiment, which may be used with theforty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitfurther comprises a second cell including a second bipolar membrane anda third ion exchange membrane, wherein the second cell is positionednext to the first cell, and wherein the second bipolar membrane ispositioned between the second ion exchange membrane of the first celland the third ion exchange membrane, thereby forming a third compartmentbetween the second bipolar membrane and the third ion exchange membrane.

In a fifty-first general embodiment, which may be used with the fiftiethembodiment in combination with any other embodiment described hereinunless specified otherwise, the first, second, and third ion exchangemembranes are cation exchange membranes or the first, second, and thirdion exchange membranes are anion exchange membranes.

In a fifty-second general embodiment, which may be used with theforty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitcomprises a cell including a first bipolar membrane, a second bipolarmembrane, a first ion exchange membrane, and a second ion exchangemembrane, wherein the first ion exchange membrane and the second ionexchange membrane are positioned between the first bipolar membrane andthe second bipolar membrane, thereby forming a first compartment betweenthe first bipolar membrane and the first ion exchange membrane, a secondcompartment between the first ion exchange membrane and the second ionexchange membrane, and a third compartment between the second ionexchange membrane and the second bipolar membrane.

In a fifty-third general embodiment, which may be used with thefifty-second embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the first ion exchangemembrane is a cation exchange membrane and the second ion exchangemembrane is an anion exchange membrane.

In a fifty-fourth general embodiment, which may be used with theforty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, a power source in the ureadecomposition unit provides the electrodes with an electrical charge toactivate the electrocatalytic surface of the electrodes.

In a fifty-fifth general embodiment, which may be used with theforty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, a power source in theelectrodialysis unit provides the electrodes with an electrical chargeto split water in a bipolar membrane into H⁺ and OH⁻.

In a fifty-sixth general embodiment, which may be used with theforty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitseparates the salt solution via bipolar membrane electrodialysis.

In a fifty-seventh general embodiment, which may be used with theforty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the salt solution is adialysis fluid.

In a fifty-eighth general embodiment, which may be used with thefifty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the dialysis fluid includesone or more salts selected from the group consisting of: a sodium salt,a magnesium salt, a calcium salt, lactate, carbonate, acetate, citrate,or phosphate.

In a fifty-ninth general embodiment, which may be used with theforty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the device further includesa tank for the salt solution.

In a sixtieth general embodiment, which may be used with the forty-sixthembodiment in combination with any other embodiment described hereinunless specified otherwise, the basic stream includes NaOH.

In a sixty-first general embodiment, which may be used with theforty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the acid stream includesHCl.

In a sixty-second general embodiment, which may be used with theforty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the anodes in the ureadecomposition unit comprise a transition metal and/or mixtures thereofand/or alloys thereof.

In a sixty-third general embodiment, which may be used with thesixty-second embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the transition metal iscobalt, copper, iron, nickel, platinum, palladium, iridium, ruthenium,or rhodium.

In a sixty-fourth general embodiment, which may be used with thesixty-second embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the anodes in the ureadecomposition unit comprise nickel, nickel oxide, nickel hydroxide ornickel oxide hydroxide (NiOOH).

In a sixty-fifth general embodiment, which may be used with theforty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the urea decomposition unitincludes an alkaline polymeric gel.

In a sixty-sixth general embodiment, which may be used with theforty-sixth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, a voltage differenceapplied across the cathodes and the anodes in the urea decompositionunit is sufficient to produce nitrogen gas, carbon dioxide gas, andwater.

In a sixty-seventh general embodiment, which may be used in combinationwith any other embodiment described herein unless specified otherwise, amethod of cleaning a used dialysis fluid having urea to produce acleansed dialysis fluid includes passing a used dialysis fluid havingurea through a device. The device includes: a urea decomposition unitcomprising an inlet for entry of the used dialysis fluid having urea andan outlet for removal of the cleansed dialysis fluid, and a set ofelectrodes having an anode and a cathode with an electrocatalyticsurface for decomposition of urea via electrooxidation; and anelectrodialysis unit comprising a set of electrodes having an anode anda cathode with an electrocatalytic surface for separation of a saltsolution via electrodialysis, where the salt solution is separated intoan acid stream and a basic stream, wherein at least one of (i) the basicstream of the electrodialysis unit is placed in fluid communication withthe inlet of the urea decomposition unit, (ii) the acid stream from theelectrodialysis unit is in fluid communication with the outlet of theurea decomposition unit, or (iii) the acid stream is circulated throughthe electrodialysis unit, and wherein the dialysis fluid exiting theoutlet of the urea decomposition unit is cleansed dialysis fluid.

In a sixty-eighth general embodiment, which may be used with thesixty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitcomprises a first cell including a first bipolar membrane, a first ionexchange membrane, and a second ion exchange membrane, wherein the firstion exchange membrane is positioned next to one side of the firstbipolar membrane and the second ion exchange membrane is positioned nextto an opposite side of the first bipolar membrane, thereby forming afirst compartment between the first bipolar membrane and the first ionexchange membrane and a second compartment between the first bipolarmembrane and the second ion exchange membrane.

In a sixty-ninth general embodiment, which may be used with thesixty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the first ion exchangemembrane is an anion exchange membrane or a cation exchange membrane.

In a seventieth general embodiment, which may be used with thesixty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the second ion exchangemembrane is an anion exchange membrane or a cation exchange membrane.

In a seventy-first general embodiment, which may be used with thesixty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitfurther comprises a second cell including a second bipolar membrane anda third ion exchange membrane, wherein the second cell is positionednext to the first cell, and wherein the second bipolar membrane ispositioned between the second ion exchange membrane of the first celland the third ion exchange membrane, thereby forming a third compartmentbetween the second bipolar membrane and the third ion exchange membrane.

In a seventy-second general embodiment, which may be used with theseventy-first embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the first, second, andthird ion exchange membranes are cation exchange membranes or the first,second, and third ion exchange membranes are anion exchange membranes.

In a seventy-third general embodiment, which may be used with thesixty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitcomprises a cell including a first bipolar membrane, a second bipolarmembrane, a first ion exchange membrane, and a second ion exchangemembrane, wherein the first ion exchange membrane and the second ionexchange membrane are positioned between the first bipolar membrane andthe second bipolar membrane, thereby forming a first compartment betweenthe first bipolar membrane and the first ion exchange membrane, a secondcompartment between the first ion exchange membrane and the second ionexchange membrane, and a third compartment between the second ionexchange membrane and the second bipolar membrane.

In a seventy-fourth general embodiment, which may be used with theseventy-third embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the first ion exchangemembrane is a cation exchange membrane and the second ion exchangemembrane is an anion exchange membrane.

In a seventy-fifth general embodiment, which may be used with thesixty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, a power source in the ureadecomposition unit provides the electrodes with an electrical charge toactivate the electrocatalytic surface of the electrodes.

In a seventy-sixth general embodiment, which may be used with thesixty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, a power source in theelectrodialysis unit provides the electrodes with an electrical chargeto split water in a bipolar membrane into H⁺ and OH⁻.

In a seventy-seventh general embodiment, which may be used with thesixty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitseparates the salt solution via bipolar membrane electrodialysis.

In a seventy-eighth general embodiment, which may be used with thesixty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the salt solution is adialysis fluid.

In a seventy-ninth general embodiment, which may be used with theseventy-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the dialysis fluid includesone or more salts selected from the group consisting of: a sodium salt,a magnesium salt, a calcium salt, lactate, carbonate, acetate, citrate,or phosphate.

In an eightieth general embodiment, which may be used with thesixty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the device includes a tankfor the salt solution.

In an eighty-first general embodiment, which may be used with thesixty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the basic stream includesNaOH.

In an eighty-second general embodiment, which may be used with thesixty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the acid stream includesHCl.

In an eighty-third general embodiment, which may be used with thesixty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the anodes in the ureadecomposition unit comprise a transition metal and/or mixtures thereofand/or alloys thereof.

In an eighty-fourth general embodiment, which may be used with theeighty-third embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the transition metal iscobalt, copper, iron, nickel, platinum, palladium, iridium, ruthenium,or rhodium.

In an eighty-fifth general embodiment, which may be used with theeighty-third embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the anodes in the ureadecomposition unit comprise nickel, nickel oxide, nickel hydroxide ornickel oxide hydroxide (NiOOH).

In an eighty-sixth general embodiment, which may be used with thesixty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the urea decomposition unitincludes an alkaline polymeric gel.

In an eighty-seventh general embodiment, which may be used with thesixty-seventh embodiment in combination with any other embodimentdescribed herein unless specified otherwise, a voltage differenceapplied across the cathodes and the anodes in the urea decompositionunit is sufficient to produce nitrogen gas, carbon dioxide gas, andwater.

In an eighty-eighth general embodiment, which may be used in combinationwith any other embodiment described herein unless specified otherwise, ahemodialysis system that recycles a dialysis fluid includes a bloodcircuit and a dialysis fluid circuit, wherein the dialysis fluid circuitis in fluid communication with a device that removes urea from a useddialysis fluid having urea to produce a cleansed dialysis fluid. Thedevice includes: a urea decomposition unit comprising an inlet for entryof the used dialysis fluid having urea and an outlet for removal of thecleansed dialysis fluid, and a set of electrodes having an anode and acathode with an electrocatalytic surface for decomposition of urea viaelectrooxidation; and an electrodialysis unit comprising a set ofelectrodes having an anode and a cathode with an electrocatalyticsurface for separation of a salt solution via electrodialysis, where thesalt solution is separated into an acid stream and a basic stream,wherein at least one of (i) the basic stream of the electrodialysis unitis placed in fluid communication with the inlet of the ureadecomposition unit, (ii) the acid stream from the electrodialysis unitis in fluid communication with the outlet of the urea decompositionunit, or (iii) the acid stream is circulated through the electrodialysisunit, and wherein the dialysis fluid exiting the outlet of the ureadecomposition unit is cleansed dialysis fluid.

In an eighty-ninth general embodiment, which may be used with theeighty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitcomprises a first cell including a first bipolar membrane, a first ionexchange membrane, and a second ion exchange membrane, wherein the firstion exchange membrane is positioned next to one side of the firstbipolar membrane and the second ion exchange membrane is positioned nextto an opposite side of the first bipolar membrane, thereby forming afirst compartment between the first bipolar membrane and the first ionexchange membrane and a second compartment between the first bipolarmembrane and the second ion exchange membrane.

In a ninetieth general embodiment, which may be used with theeighty-ninth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the first ion exchangemembrane is an anion exchange membrane or a cation exchange membrane.

In a ninety-first general embodiment, which may be used with theeighty-ninth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the second ion exchangemembrane is an anion exchange membrane or a cation exchange membrane.

In a ninety-second general embodiment, which may be used with theeighty-ninth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitfurther comprises a second cell including a second bipolar membrane anda third ion exchange membrane, wherein the second cell is positionednext to the first cell, and wherein the second bipolar membrane ispositioned between the second ion exchange membrane of the first celland the third ion exchange membrane, thereby forming a third compartmentbetween the second bipolar membrane and the third ion exchange membrane.

In a ninety-third general embodiment, which may be used with theninety-second embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the first, second, andthird ion exchange membranes are cation exchange membranes or the first,second, and third ion exchange membranes are anion exchange membranes.

In a ninety-fourth general embodiment, which may be used with theeighty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitcomprises a cell including a first bipolar membrane, a second bipolarmembrane, a first ion exchange membrane, and a second ion exchangemembrane, wherein the first ion exchange membrane and the second ionexchange membrane are positioned between the first bipolar membrane andthe second bipolar membrane, thereby forming a first compartment betweenthe first bipolar membrane and the first ion exchange membrane, a secondcompartment between the first ion exchange membrane and the second ionexchange membrane, and a third compartment between the second ionexchange membrane and the second bipolar membrane.

In a ninety-fifth general embodiment, which may be used with theninety-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the first ion exchange is acation exchange membrane and the second ion exchange membrane is ananion exchange membrane.

In a ninety-sixth general embodiment, which may be used with theeighty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, a power source in the ureadecomposition unit provides the electrodes with an electrical charge toactivate the electrocatalytic surface of the electrodes.

In a ninety-seventh general embodiment, which may be used with theeighty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, a power source in theelectrodialysis unit provides the electrodes with an electrical chargeto split water in a bipolar membrane into H⁺ and OH⁻.

In a ninety-eighth general embodiment, which may be used with theeighty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the electrodialysis unitseparates the salt solution via bipolar membrane electrodialysis.

In a ninety-ninth general embodiment, which may be used with theeighty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the salt solution is adialysis fluid.

In a one-hundredth general embodiment, which may be used with theninety-ninth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the dialysis fluid includesone or more salts selected from the group consisting of: a sodium salt,a magnesium salt, a calcium salt, lactate, carbonate, acetate, citrate,or phosphate.

In a one-hundred-first general embodiment, which may be used with theeighty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the device includes a tankfor the salt solution.

In a one-hundred-second general embodiment, which may be used with theeighty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the basic stream includesNaOH.

In a one-hundred-third general embodiment, which may be used with theeighty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the acid stream includesHCl.

In a one-hundred-fourth general embodiment, which may be used with theeighty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the anodes in the ureadecomposition unit comprise a transition metal and/or mixtures thereofand/or alloys thereof.

In a one-hundred-fifth general embodiment, which may be used with theone-hundred-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the transition metal iscobalt, copper, iron, nickel, platinum, palladium, iridium, ruthenium,or rhodium.

In a one-hundred-sixth general embodiment, which may be used with theone-hundred-fourth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the anodes in the ureadecomposition unit comprise nickel, nickel oxide, nickel hydroxide ornickel oxide hydroxide (NiOOH).

In a one-hundred-seventh general embodiment, which may be used with theeighty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the urea decomposition unitincludes an alkaline polymeric gel.

In a one-hundred-eighth general embodiment, which may be used with theeighty-eighth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, a voltage differenceapplied across the cathodes and the anodes in the urea decompositionunit is sufficient to produce nitrogen gas, carbon dioxide gas, andwater.

In a one-hundred-ninth general embodiment, which may be used incombination with any other embodiment described herein unless specifiedotherwise, a device for the removal of urea from a fluid having urea toproduce a cleansed fluid includes: a combination electrodialysis andurea oxidation cell including: a first set of electrodes for separationof the fluid into an acid stream and a basic stream, wherein the firstset of electrodes includes an anode and a cathode; one or more secondset of electrodes positioned to contact the basic stream with anelectrocatalytic surface for decomposition of urea via electrooxidation;and at least one power source to provide the first and second set ofelectrodes with an electrical charge to activate the electrocatalyticsurface.

In a one-hundred-tenth general embodiment, which may be used with theone-hundred-ninth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the combinationelectrodialysis and urea oxidation cell comprises a first cell includinga first bipolar membrane, a first ion exchange membrane, and a secondion exchange membrane, wherein the first ion exchange membrane ispositioned next to one side of the first bipolar membrane and the secondion exchange membrane is positioned next to an opposite side of thefirst bipolar membrane, thereby forming a first compartment between thefirst bipolar membrane and the first ion exchange membrane and a secondcompartment between the first bipolar membrane and the second ionexchange membrane, and wherein the one or more second set of electrodesis positioned in the first compartment.

In a one-hundred-eleventh general embodiment, which may be used with theone-hundred-tenth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the first ion exchangemembrane is an anion exchange membrane or a cation exchange membrane.

In a one-hundred-twelfth general embodiment, which may be used with theone-hundred-tenth embodiment in combination with any other embodimentdescribed herein unless specified otherwise, the second ion exchangemembrane is an anion exchange membrane or a cation exchange membrane.

In a one-hundred-thirteenth general embodiment, which may be used withthe one-hundred-tenth embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationelectrodialysis and urea oxidation cell further comprises a second cellincluding a second bipolar membrane and a third ion exchange membrane,wherein the second cell is positioned next to the first cell, andwherein the second bipolar membrane is positioned between the second ionexchange membrane of the first cell and the third ion exchange membrane,thereby forming a third compartment between the second bipolar membraneand the third ion exchange membrane, and wherein one or more third setof electrodes having an electrocatalytic surface for decomposition ofurea via electrooxidation is positioned between the second ion exchangemembrane and the second bipolar membrane.

In a one-hundred-fourteenth general embodiment, which may be used withthe one-hundred-thirteenth embodiment in combination with any otherembodiment described herein unless specified otherwise, the first,second, and third ion exchange membranes are cation exchange membranesor wherein the first, second, and third ion exchange membranes are anionexchange membranes.

In a one-hundred-fifteenth general embodiment, which may be used withthe one-hundred-ninth embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationelectrodialysis and urea oxidation cell further comprises a firstbipolar membrane, a second bipolar membrane, a first ion exchangemembrane, and a second ion exchange membrane, wherein the first ionexchange membrane and the second ion exchange membrane are positionedbetween the first bipolar membrane and the second bipolar membrane,thereby forming a first compartment between the first bipolar membraneand the first ion exchange membrane, a second compartment between thefirst ion exchange membrane and the second ion exchange membrane, and athird compartment between the second ion exchange membrane and thesecond bipolar membrane.

In a one-hundred-sixteenth general embodiment, which may be used withthe one-hundred-fifteenth embodiment in combination with any otherembodiment described herein unless specified otherwise, the first ionexchange membrane is a cation exchange membrane and the second ionexchange membrane is an anion exchange membrane.

In a one-hundred-seventeenth general embodiment, which may be used withthe one-hundred-ninth embodiment in combination with any otherembodiment described herein unless specified otherwise, the saltsolution is a dialysis fluid.

In a one-hundred-eighteenth general embodiment, which may be used withthe one-hundred-seventeenth embodiment in combination with any otherembodiment described herein unless specified otherwise, the dialysisfluid includes one or more salts selected from the group consisting of:a sodium salt, a magnesium salt, a calcium salt, lactate, carbonate,acetate, citrate, or phosphate.

In a one-hundred-nineteenth general embodiment, which may be used withthe one-hundred-ninth embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationcell includes a tank for the fluid.

In a one-hundred-twentieth general embodiment, which may be used withthe one-hundred-ninth embodiment in combination with any otherembodiment described herein unless specified otherwise, the basic streamincludes NaOH.

In a one-hundred-twenty-first general embodiment, which may be used withthe one-hundred-ninth embodiment in combination with any otherembodiment described herein unless specified otherwise, the acid streamincludes HCl.

In a one-hundred-twenty-second general embodiment, which may be usedwith the one-hundred-ninth embodiment in combination with any otherembodiment described herein unless specified otherwise, the anodes ofthe set of second electrodes comprise a transition metal and/or mixturesthereof and/or alloys thereof.

In a one-hundred-twenty-third general embodiment, which may be used withthe one-hundred-twenty-second embodiment in combination with any otherembodiment described herein unless specified otherwise, the transitionmetal is cobalt, copper, iron, nickel, platinum, palladium, iridium,ruthenium, or rhodium.

In a one-hundred-twenty-fourth general embodiment, which may be usedwith the one-hundred-twenty-second embodiment in combination with anyother embodiment described herein unless specified otherwise, the anodesof the set of second electrodes comprise nickel, nickel oxide, nickelhydroxide or nickel oxide hydroxide (NiOOH).

In a one-hundred-twenty-fifth general embodiment, which may be used withthe one-hundred-ninth embodiment in combination with any otherembodiment described herein unless specified otherwise, the fluid havingurea is a dialysis fluid contaminated with urea.

In a one-hundred-twenty-sixth general embodiment, which may be used withthe one-hundred-ninth embodiment in combination with any otherembodiment described herein unless specified otherwise, a voltagedifference applied across the cathodes and the anodes in the second setof electrodes is sufficient to produce nitrogen gas, carbon dioxide gas,and water.

In a one-hundred-twenty-seventh general embodiment, which may be used incombination with any other embodiment described herein unless specifiedotherwise, a renal replacement therapy system includes a dialysis fluidcircuit. The dialysis fluid circuit includes a combinationelectrodialysis and urea oxidation cell. The combination cell includes:a first set of electrodes for separation of the dialysis fluidcontaining urea into an acid stream and a basic stream, wherein thefirst set of electrodes includes an anode and a cathode; one or moresecond set of electrodes positioned to contact the basic stream with anelectrocatalytic surface for decomposition of urea via electrooxidation;and at least one power source to provide the first and second set ofelectrodes with an electrical charge to activate the electrocatalyticsurface.

In a one-hundred-twenty-eighth general embodiment, which may be usedwith the one-hundred-twenty-seventh embodiment in combination with anyother embodiment described herein unless specified otherwise, thecombination electrodialysis and urea oxidation cell comprises a firstcell including a first bipolar membrane, a first ion exchange membrane,and a second ion exchange membrane, wherein the first ion exchangemembrane is positioned next to one side of the first bipolar membraneand the second ion exchange membrane is positioned next to an oppositeside of the first bipolar membrane, thereby forming a first compartmentbetween the first bipolar membrane and the first ion exchange membraneand a second compartment between the first bipolar membrane and thesecond ion exchange membrane, and wherein the one or more second set ofelectrodes is positioned in the first compartment.

In a one-hundred-twenty-ninth general embodiment, which may be used withthe one-hundred-twenty-eighth embodiment in combination with any otherembodiment described herein unless specified otherwise, the first ionexchange membrane is an anion exchange membrane or a cation exchangemembrane.

In a one-hundred-thirtieth general embodiment, which may be used withthe one-hundred-twenty-eighth embodiment in combination with any otherembodiment described herein unless specified otherwise, the second ionexchange membrane is an anion exchange membrane or a cation exchangemembrane.

In a one-hundred-thirty-first general embodiment, which may be used withthe one-hundred-twenty-eighth embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationelectrodialysis and urea oxidation cell further comprises a second cellcomprising a second bipolar membrane and a third ion exchange membrane,wherein the second cell is positioned next to the first cell, andwherein the second bipolar membrane is positioned between the second ionexchange membrane of the first cell and the third ion exchange membrane,thereby forming a third compartment between the second bipolar membraneand the third ion exchange membrane, and wherein one or more third setof electrodes having an electrocatalytic surface for decomposition ofurea via electrooxidation is positioned between the second ion exchangemembrane and the second bipolar membrane.

In a one-hundred-thirty-second general embodiment, which may be usedwith the one-hundred-thirty-first embodiment in combination with anyother embodiment described herein unless specified otherwise, the first,second, and third ion exchange membranes are cation exchange membranesor wherein the first, second, and third ion exchange membranes are anionexchange membranes.

In a one-hundred-thirty-third general embodiment, which may be used withthe one-hundred-twenty-seventh embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationelectrodialysis and urea oxidation cell further comprises a firstbipolar membrane, a second bipolar membrane, a first ion exchangemembrane, and a second ion exchange membrane, wherein the first ionexchange membrane and the second ion exchange membrane are positionedbetween the first bipolar membrane and the second bipolar membrane,thereby forming a first compartment between the first bipolar membraneand the first ion exchange membrane, a second compartment between thefirst ion exchange membrane and the second ion exchange membrane, and athird compartment between the second ion exchange membrane and thesecond bipolar membrane.

In a one-hundred-thirty-fourth general embodiment, which may be usedwith the one-hundred-thirty-third embodiment in combination with anyother embodiment described herein unless specified otherwise, the firstion exchange membrane is a cation exchange membrane and the second ionexchange membrane is an anion exchange membrane.

In a one-hundred-thirty-fifth general embodiment, which may be used withthe one-hundred-twenty-seventh embodiment in combination with any otherembodiment described herein unless specified otherwise, the dialysisfluid includes a salt solution.

In a one-hundred-thirty-sixth general embodiment, which may be used withthe one-hundred-twenty-seventh embodiment in combination with any otherembodiment described herein unless specified otherwise, the dialysisfluid includes one or more salts selected from the group consisting of:a sodium salt, a magnesium salt, a calcium salt, lactate, carbonate,acetate, citrate, or phosphate.

In a one-hundred-thirty-seventh general embodiment, which may be usedwith the one-hundred-twenty-seventh embodiment in combination with anyother embodiment described herein unless specified otherwise, thecombination cell includes a tank for the dialysis fluid containing urea.

In a one-hundred-thirty-eighth general embodiment, which may be usedwith the one-hundred-twenty-seventh embodiment in combination with anyother embodiment described herein unless specified otherwise, the basicstream includes NaOH.

In a one-hundred-thirty-ninth general embodiment, which may be used withthe one-hundred-twenty-seventh embodiment in combination with any otherembodiment described herein unless specified otherwise, the acid streamincludes HCl.

In a one-hundred-fortieth general embodiment, which may be used with theone-hundred-twenty-seventh embodiment in combination with any otherembodiment described herein unless specified otherwise, the anodes ofthe set of second electrodes comprise a transition metal and/or mixturesthereof and/or alloys thereof.

In a one-hundred-forty-first general embodiment, which may be used withthe one-hundred-fortieth embodiment in combination with any otherembodiment described herein unless specified otherwise, the transitionmetal is cobalt, copper, iron, nickel, platinum, palladium, iridium,ruthenium, or rhodium.

In a one-hundred-forty-second general embodiment, which may be used withthe one-hundred-fortieth embodiment in combination with any otherembodiment described herein unless specified otherwise, the anodes ofthe set of second electrodes comprise nickel, nickel oxide, nickelhydroxide or nickel oxide hydroxide (NiOOH).

In a one-hundred-forty-third general embodiment, which may be used withthe one-hundred-twenty-seventh embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationcell includes a tank for cleansed dialysis fluid.

In a one-hundred-forty-fourth general embodiment, which may be used withthe one-hundred-twenty-seventh embodiment in combination with any otherembodiment described herein unless specified otherwise, a voltagedifference applied across the cathode and the anode in the second set ofelectrodes is sufficient to produce nitrogen gas, carbon dioxide gas,and water.

In a one-hundred-forty-fifth general embodiment, which may be used incombination with any other embodiment described herein unless specifiedotherwise, a method of performing a renal replacement therapy includespassing a dialysis fluid having urea through a combinationelectrodialysis and urea oxidation cell comprising: a first set ofelectrodes for separation of the dialysis fluid having urea into an acidstream and a basic stream, wherein the first set of electrodes includesan anode and a cathode; one or more second set of electrodes positionedto contact the basic stream with an electrocatalytic surface fordecomposition of urea via electrooxidation; and at least one powersource to provide the first and second set of electrodes with anelectrical charge to activate the electrocatalytic surface.

In a one-hundred-forty-sixth general embodiment, which may be used withthe one-hundred-forty-fifth embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationelectrodialysis and urea oxidation cell comprises a first cell includingthe first bipolar membrane, a first ion exchange membrane, and a secondion exchange membrane, wherein the first ion exchange membrane ispositioned next to one side of the first bipolar membrane and the secondion exchange membrane is positioned next to an opposite side of thefirst bipolar membrane, thereby forming a first compartment between thefirst bipolar membrane and the first ion exchange membrane and a secondcompartment between the first bipolar membrane and the second ionexchange membrane, and wherein the one or more second set of electrodesis positioned in the first compartment.

In a one-hundred-forty-seventh general embodiment, which may be usedwith the one-hundred-forty-sixth embodiment in combination with anyother embodiment described herein unless specified otherwise, the firstion exchange membrane is an anion exchange membrane or a cation exchangemembrane.

In a one-hundred-forty-eighth general embodiment, which may be used withthe one-hundred-forty-sixth embodiment in combination with any otherembodiment described herein unless specified otherwise, the second ionexchange membrane is an anion exchange membrane or a cation exchangemembrane.

In a one-hundred-forty-ninth general embodiment, which may be used withthe one-hundred-forty-sixth embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationelectrodialysis and urea oxidation cell further comprises a second cellincluding a second bipolar membrane and a third ion exchange membrane,wherein the second cell is positioned next to the first cell, andwherein the second bipolar membrane is positioned between the second ionexchange membrane of the first cell and the third ion exchange membrane,thereby forming a third compartment between the second bipolar membraneand the third ion exchange membrane, and wherein one or more third setof electrodes having an electrocatalytic surface for decomposition ofurea via electrooxidation is positioned between the second ion exchangemembrane and the second bipolar membrane.

In a one-hundred-fiftieth general embodiment, which may be used with theone-hundred-forty-ninth embodiment in combination with any otherembodiment described herein unless specified otherwise, the first,second, and third ion exchange membranes are cation exchange membranesor the first, second, and third ion exchange membranes are anionexchange membranes.

In a one-hundred-fifty-first general embodiment, which may be used withthe one-hundred-forty-fifth embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationelectrodialysis and urea oxidation cell further comprises a secondbipolar membrane, a first ion exchange membrane, and a second ionexchange membrane, wherein the first ion exchange membrane and thesecond ion exchange membrane are positioned between the first bipolarmembrane and the second bipolar membrane, thereby forming a firstcompartment between the first bipolar membrane and the first ionexchange membrane, a second compartment between the first ion exchangemembrane and the second ion exchange membrane, and a third compartmentbetween the second ion exchange membrane and the second bipolar membrane

In a one-hundred-fifty-second general embodiment, which may be used withthe one-hundred-fifty-first embodiment in combination with any otherembodiment described herein unless specified otherwise, the first ionexchange membrane is a cation exchange membrane and the second ionexchange membrane is an anion exchange membrane.

In a one-hundred-fifty-third general embodiment, which may be used withthe one-hundred-forty-fifth embodiment in combination with any otherembodiment described herein unless specified otherwise, the dialysisfluid includes a salt solution.

In a one-hundred-fifty-fourth general embodiment, which may be used withthe one-hundred-forty-fifth embodiment in combination with any otherembodiment described herein unless specified otherwise, the dialysisfluid includes one or more salts selected from the group consisting of:a sodium salt, a magnesium salt, a calcium salt, lactate, carbonate,acetate, citrate, or phosphate.

In a one-hundred-fifty-fifth general embodiment, which may be used withthe one-hundred-forty-fifth embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationcell includes a tank for the dialysis fluid containing urea.

In a one-hundred-fifty-sixth general embodiment, which may be used withthe one-hundred-forty-fifth embodiment in combination with any otherembodiment described herein unless specified otherwise, the basic streamincludes NaOH.

In a one-hundred-fifty-seventh general embodiment, which may be usedwith the one-hundred-forty-fifth embodiment in combination with anyother embodiment described herein unless specified otherwise, the acidstream includes HCl.

In a one-hundred-fifty-eighth general embodiment, which may be used withthe one-hundred-forty-fifth embodiment in combination with any otherembodiment described herein unless specified otherwise, the anodes ofthe set of second electrodes comprise a transition metal and/or mixturesthereof and/or alloys thereof.

In a one-hundred-fifty-ninth general embodiment, which may be used withthe one-hundred-fifty-eighth embodiment in combination with any otherembodiment described herein unless specified otherwise, the transitionmetal is cobalt, copper, iron, nickel, platinum, palladium, iridium,ruthenium, or rhodium.

In a one-hundred-sixtieth general embodiment, which may be used with theone-hundred-fifty-eighth embodiment in combination with any otherembodiment described herein unless specified otherwise, the anodes ofthe set of second electrodes comprise nickel, nickel oxide, nickelhydroxide or nickel oxide hydroxide (NiOOH).

In a one-hundred-sixty-first general embodiment, which may be used withthe one-hundred-forty-fifth embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationcell includes a tank for cleansed dialysis fluid.

In a one-hundred-sixty-second general embodiment, which may be used withthe one-hundred-forty-fifth embodiment in combination with any otherembodiment described herein unless specified otherwise, a voltagedifference applied across the cathodes and the anodes in the second setof electrodes is sufficient to produce nitrogen gas, carbon dioxide gas,and water.

In a one-hundred-sixty-third general embodiment, which may be used incombination with any other embodiment described herein unless specifiedotherwise, a method of cleaning a used dialysis fluid having urea toproduce a clean dialysis fluid includes passing a used dialysis fluidhaving urea through a combination electrodialysis and urea oxidationcell. The combination cell includes a first set of electrodes forseparation of the dialysis fluid having urea into an acid stream and abasic stream, wherein the first set of electrodes includes an anode anda cathode; one or more second set of electrodes positioned to contactthe basic stream with an electrocatalytic surface for decomposition ofurea via electrooxidation; and at least one power source to provide thefirst and second set of electrodes with an electrical charge to activatethe electrocatalytic surface.

In a one-hundred-sixty-fourth general embodiment, which may be used withthe one-hundred-sixty-third embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationelectrodialysis and urea oxidation cell comprises a first cell includingthe first bipolar membrane, a first ion exchange membrane, and a secondion exchange membrane, wherein the first ion exchange membrane ispositioned next to one side of the first bipolar membrane and the secondion exchange membrane is positioned next to an opposite side of thefirst bipolar membrane, thereby forming a first compartment between thefirst bipolar membrane and the first ion exchange membrane and a secondcompartment between the first bipolar membrane and the second ionexchange membrane, and wherein the one or more second set of electrodesis positioned in the first compartment.

In a one-hundred-sixty-fifth general embodiment, which may be used withthe one-hundred-sixty-fourth embodiment in combination with any otherembodiment described herein unless specified otherwise, the first ionexchange membrane is an anion exchange membrane or a cation exchangemembrane.

In a one-hundred-sixty-sixth general embodiment, which may be used withthe one-hundred-sixty-fourth embodiment in combination with any otherembodiment described herein unless specified otherwise, the second ionexchange membrane is an anion exchange membrane or a cation exchangemembrane.

In a one-hundred-sixty-seventh general embodiment, which may be usedwith the one-hundred-sixty-fourth embodiment in combination with anyother embodiment described herein unless specified otherwise, thecombination electrodialysis and urea oxidation cell further comprises asecond cell including a second bipolar membrane and a third ion exchangemembrane, wherein the second cell is positioned next to the first cell,and wherein the second bipolar membrane is positioned between the secondion exchange membrane of the first cell and the third ion exchangemembrane, thereby forming a third compartment between the second bipolarmembrane and the third ion exchange membrane, and wherein one or morethird set of electrodes having an electrocatalytic surface fordecomposition of urea via electrooxidation is positioned between thesecond ion exchange membrane and the second bipolar membrane.

In a one-hundred-sixty-eighth general embodiment, which may be used withthe one-hundred-sixty-seventh embodiment in combination with any otherembodiment described herein unless specified otherwise, the first,second, and third ion exchange membranes are cation exchange membranesor wherein the first, second, and third ion exchange membranes are anionexchange membranes.

In a one-hundred-sixty-ninth general embodiment, which may be used withthe one-hundred-sixty-third embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationelectrodialysis and urea oxidation cell further comprises a secondbipolar membrane, a first ion exchange membrane, and a second ionexchange membrane, wherein the first ion exchange membrane and thesecond ion exchange membrane are positioned between the first bipolarmembrane and the second bipolar membrane, thereby forming a firstcompartment between the first bipolar membrane and the first ionexchange membrane, a second compartment between the first ion exchangemembrane and the second ion exchange membrane, and a third compartmentbetween the second ion exchange membrane and the second bipolarmembrane.

In a one-hundred-seventieth general embodiment, which may be used withthe one-hundred-sixty-ninth embodiment in combination with any otherembodiment described herein unless specified otherwise, the first ionexchange membrane is a cation exchange membrane and the second ionexchange membrane is an anion exchange membrane.

In a one-hundred-seventy-first general embodiment, which may be usedwith the one-hundred-sixty-third embodiment in combination with anyother embodiment described herein unless specified otherwise, thedialysis fluid includes a salt solution.

In a one-hundred-seventy-second general embodiment, which may be usedwith the one-hundred-sixty-third embodiment in combination with anyother embodiment described herein unless specified otherwise, thedialysis fluid includes one or more salts selected from the groupconsisting of: a sodium salt, a magnesium salt, a calcium salt, lactate,carbonate, acetate, citrate, or phosphate.

In a one-hundred-seventy-third general embodiment, which may be usedwith the one-hundred-sixty-third embodiment in combination with anyother embodiment described herein unless specified otherwise, thecombination cell includes a tank for the salt solution.

In a one-hundred-seventy-fourth general embodiment, which may be usedwith the one-hundred-sixty-third embodiment in combination with anyother embodiment described herein unless specified otherwise, the basicstream includes NaOH.

In a one-hundred-seventy-fifth general embodiment, which may be usedwith the one-hundred-sixty-third embodiment in combination with anyother embodiment described herein unless specified otherwise, the acidstream includes HCl.

In a one-hundred-seventy-sixth general embodiment, which may be usedwith the one-hundred-sixty-third embodiment in combination with anyother embodiment described herein unless specified otherwise, the anodesof the set of second electrodes comprise a transition metal and/ormixtures thereof and/or alloys thereof.

In a one-hundred-seventy-seventh general embodiment, which may be usedwith the one-hundred-seventy-sixth embodiment in combination with anyother embodiment described herein unless specified otherwise, thetransition metal is cobalt, copper, iron, nickel, platinum, palladium,iridium, ruthenium, or rhodium.

In a one-hundred-seventy-eighth general embodiment, which may be usedwith the one-hundred-seventy-sixth embodiment in combination with anyother embodiment described herein unless specified otherwise, the anodesof the set of second electrodes comprise nickel, nickel oxide, nickelhydroxide or nickel oxide hydroxide (NiOOH).

In a one-hundred-seventy-ninth general embodiment, which may be usedwith the one-hundred-sixty-third embodiment in combination with anyother embodiment described herein unless specified otherwise, thecombination cell includes a tank for the dialysis fluid having urea.

In a one-hundred-eightieth general embodiment, which may be used withthe one-hundred-sixty-third embodiment in combination with any otherembodiment described herein unless specified otherwise, a voltagedifference applied across the cathodes and the anodes in the second setof electrodes is sufficient to produce nitrogen gas, carbon dioxide gas,and water.

In a one-hundred-eighty-first general embodiment, which may be used incombination with any other embodiment described herein unless specifiedotherwise, a hemodialysis system that recycles a dialysis fluid includesa blood circuit and a dialysis fluid circuit, wherein the dialysis fluidcircuit is in fluid communication with a combination electrodialysis andurea oxidation cell comprising: a first set of electrodes with anelectrocatalytic surface for separation of dialysis fluid having ureainto an acid stream and a basic stream, wherein the first set ofelectrodes includes an anode and a cathode; one or more second set ofelectrodes positioned to contact the basic stream with anelectrocatalytic surface for decomposition of urea via electrooxidation;and at least one power source to provide the first and second set ofelectrodes with an electrical charge to activate the electrocatalyticsurface.

In a one-hundred-eighty-second general embodiment, which may be usedwith the one-hundred-eighty-first embodiment in combination with anyother embodiment described herein unless specified otherwise, thecombination electrodialysis and urea oxidation cell comprises a firstcell including the first bipolar membrane, a first ion exchangemembrane, and a second ion exchange membrane, wherein the first ionexchange membrane is positioned next to one side of the first bipolarmembrane and the second ion exchange membrane is positioned next to anopposite side of the first bipolar membrane, thereby forming a firstcompartment between the first bipolar membrane and the first ionexchange membrane and a second compartment between the first bipolarmembrane and the second ion exchange membrane, and wherein the one ormore second set of electrodes is positioned in the first compartment.

In a one-hundred-eighty-third general embodiment, which may be used withthe one-hundred-eighty-second embodiment in combination with any otherembodiment described herein unless specified otherwise, the first ionexchange membrane is an anion exchange membrane or a cation exchangemembrane.

In a one-hundred-eighty-fourth general embodiment, which may be usedwith the one-hundred-eighty-second embodiment in combination with anyother embodiment described herein unless specified otherwise, the secondion exchange membrane is an anion exchange membrane or a cation exchangemembrane.

In a one-hundred-eighty-fifth general embodiment, which may be used withthe one-hundred-eighty-second embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationelectrodialysis and urea oxidation cell further comprises a second cellincluding a second bipolar membrane and a third ion exchange membrane,wherein the second cell is positioned next to the first cell, andwherein the second bipolar membrane is positioned between the second ionexchange membrane of the first cell and the third ion exchange membrane,thereby forming a third compartment between the second bipolar membraneand the third ion exchange membrane, and wherein one or more third setof electrodes having an electrocatalytic surface for decomposition ofurea via electrooxidation is positioned between the second ion exchangemembrane and the second bipolar membrane.

In a one-hundred-eighty-sixth general embodiment, which may be used withthe one-hundred-eighty-fifth embodiment in combination with any otherembodiment described herein unless specified otherwise, the first,second, and third ion exchange membranes are cation exchange membranesor wherein the first, second, and third ion exchange membranes are anionexchange membranes.

In a one-hundred-eighty-seventh general embodiment, which may be usedwith the one-hundred-eighty-first embodiment in combination with anyother embodiment described herein unless specified otherwise, thecombination electrodialysis and urea oxidation cell further comprises asecond bipolar membrane, a first ion exchange membrane, and a second ionexchange membrane, wherein the first ion exchange membrane and thesecond ion exchange membrane are positioned between the first bipolarmembrane and the second bipolar membrane, thereby forming a firstcompartment between the first bipolar membrane and the first ionexchange membrane, a second compartment between the first ion exchangemembrane and the second ion exchange membrane, and a third compartmentbetween the second ion exchange membrane and the second bipolarmembrane.

In a one-hundred-eighty-eighth general embodiment, which may be usedwith the one-hundred-eighty-seventh embodiment in combination with anyother embodiment described herein unless specified otherwise, the firstion exchange membrane is a cation exchange membrane and the second ionexchange membrane is an anion exchange membrane.

In a one-hundred-eighty-ninth general embodiment, which may be used withthe one-hundred-eighty-first embodiment in combination with any otherembodiment described herein unless specified otherwise, the dialysisfluid includes a salt solution.

In a one-hundred-ninetieth general embodiment, which may be used withthe one-hundred-eighty-first embodiment in combination with any otherembodiment described herein unless specified otherwise, the dialysisfluid includes one or more salts selected from the group consisting of:a sodium salt, a magnesium salt, a calcium salt, lactate, carbonate,acetate, citrate, or phosphate.

In a one-hundred-ninety-first general embodiment, which may be used withthe one-hundred-eighty-first embodiment in combination with any otherembodiment described herein unless specified otherwise, the combinationcell includes a tank for the fluid having urea.

In a one-hundred-ninety-second general embodiment, which may be usedwith the one-hundred-eighty-first embodiment in combination with anyother embodiment described herein unless specified otherwise, the basicstream includes NaOH.

In a one-hundred-ninety-third general embodiment, which may be used withthe one-hundred-eighty-first embodiment in combination with any otherembodiment described herein unless specified otherwise, the acid streamincludes HCl.

In a one-hundred-ninety-fourth general embodiment, which may be usedwith the one-hundred-eighty-first embodiment in combination with anyother embodiment described herein unless specified otherwise, the anodesof the set of second electrodes comprise a transition metal and/ormixtures thereof and/or alloys thereof.

In a one-hundred-ninety-fifth general embodiment, which may be used withthe one-hundred-ninety-fourth embodiment in combination with any otherembodiment described herein unless specified otherwise, the transitionmetal is cobalt, copper, iron, nickel, platinum, palladium, iridium,ruthenium, or rhodium.

In a one-hundred-ninety-sixth general embodiment, which may be used withthe one-hundred-ninety-fourth embodiment in combination with any otherembodiment described herein unless specified otherwise, the anodes ofthe set of second electrodes comprise nickel, nickel oxide, nickelhydroxide or nickel oxide hydroxide (NiOOH).

In a one-hundred-ninety-seventh general embodiment, which may be usedwith the one-hundred-eighty-first embodiment in combination with anyother embodiment described herein unless specified otherwise, thecombination cell includes a tank for cleansed dialysis fluid.

In a one-hundred-ninety-eighth general embodiment, which may be usedwith the one-hundred-eighty-first embodiment in combination with anyother embodiment described herein unless specified otherwise, a voltagedifference applied across the cathodes and the anodes in the second setof electrodes is sufficient to produce nitrogen gas, carbon dioxide gas,and water.

In a one-hundred-ninety-ninth embodiment, which may be combined with anyother embodiment discussed herein unless specified otherwise, any one,or more, or all of a controller, one or more pump, valves, pH sensors,and/or flowmeters may be employed to produce a desired flow regime.

In a two-hundredth embodiment, any of the structure, functionality andalternative embodiments associated with any of FIGS. 1 to 14 may be usedwith any of the structure, functionality and alternative embodimentsassociated with any one or more other FIGS. 1 to 14.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing summary, as well as the following detailed description ofthe disclosure, will be better understood when read in conjunction withthe appended figures. For the purpose of illustrating the disclosure,shown in the figures are embodiments which may be presently preferred.It should be understood, however, that the disclosure is not limited tothe precise arrangements, examples and instrumentalities shown.Additionally, the embodiments described and claimed herein do not haveto have each of the features and advantages listed herein.

FIG. 1 shows an embodiment of a device for the removal of urea from afluid having urea to produce a cleansed fluid.

FIG. 2 shows an embodiment of a urea decomposition unit.

FIG. 3 shows an embodiment of an electrodialysis unit.

FIG. 4 shows an alternative embodiment of an electrodialysis unit.

FIG. 5 shows an alternative embodiment of a device for the removal ofurea from a fluid having urea to produce a cleansed fluid.

FIG. 6 shows an alternative embodiment of an electrodialysis unit.

FIG. 7 shows an alternative embodiment of a device for the removal ofurea from a fluid having urea to produce a cleansed fluid.

FIG. 8 shows an alternative embodiment of a device for the removal ofurea from a fluid having urea to produce a cleansed fluid.

FIG. 9 shows an alternative embodiment of a device for the removal ofurea from a fluid having urea to produce a cleansed fluid.

FIG. 10 shows an alternative embodiment of a device for the removal ofurea from a fluid having urea to produce a cleansed fluid.

FIG. 11 shows an alternative embodiment of a device for the removal ofurea from a fluid having urea to produce a cleansed fluid.

FIG. 12 shows an alternative embodiment of a device for the removal ofurea from a fluid having urea to produce a cleansed fluid.

FIG. 13 shows an alternative embodiment of a device for the removal ofurea from a fluid having urea to produce a cleansed fluid.

FIG. 14 shows an alternative embodiment of a device for the removal ofurea from a fluid having urea to produce a cleansed fluid.

DETAILED DESCRIPTION

The present disclosure provides devices and methods of using same forcleansing a solution (e.g., a salt solution) comprising urea viaelectrooxidation, and more specifically to cleansing a renal therapysolution/dialysis solution comprising urea via electrooxidation so thatthe renal therapy solution/dialysis solution can be used or reused fortreatment of a patient.

FIG. 1 illustrates an embodiment of a device 10 for the removal of ureafrom a fluid having urea to produce a cleansed fluid. In the illustratedembodiment, device 10 includes a urea decomposition unit 50 and anelectrodialysis unit 100. In use, and as explained in greater detailbelow, fluid having urea, such as dialysis fluid, can be cleansed of theurea by the combination of urea decomposition unit 50 andelectrodialysis unit 100. Urea decomposition unit 50 is illustrated inmore detail in FIG. 2, and electrodialysis unit 100 is illustrated inmore detail in FIG. 3.

FIG. 2 illustrates urea decomposition unit 50, which is configured tooxidize urea into, for example, nitrogen, hydrogen, carbon dioxide andother organic byproducts, so that fluid containing urea can be cleansedof the urea. In the illustrated embodiment, urea decomposition unit 50includes an inlet 52 for the entry of fluid having urea and an outlet 54for the removal of cleansed fluid. Urea decomposition unit 50 can alsooptionally include a second inlet 52 a (see FIG. 1) to receive a basicsolution separate from an original salt solution to be cleansed of urea.

Urea decomposition unit 50 also includes one or more sets of electrodes56 with electrocatalytic surfaces for the decomposition of urea viaelectrooxidation. Each set of electrodes 56 can include an anode and acathode. In an embodiment, the electrodes 56 include a cathode and ananode, and the anodes comprise a transition metal and/or mixturesthereof and/or alloys thereof. The transition metal can be selected fromthe group consisting of cobalt, copper, iron, nickel, platinum,palladium, iridium, ruthenium, and rhodium. In an embodiment, thecathode can include platinum and the anode comprises wherein the anodecomprises nickel, nickel oxide, nickel hydroxide or nickel oxidehydroxide (NiOOH). The urea decomposition unit 50 can also include analkaline polymeric gel.

Urea decomposition unit 50 further includes a power source 58 to providethe electrodes 56 with an electrical charge. The power source 58provides the electrodes 56 with an electrical charge to activate anelectrocatalytic surface of the electrodes. The voltage differenceapplied across the electrodes (e.g. cathode and anode) can be sufficientto produce nitrogen gas, carbon dioxide gas, and water.

In use, fluid containing urea passes into urea decomposition unit 50 viainlet 52. The power source then charges the electrodes, which create anelectrical current sufficient to oxidize the urea in the fluid into, forexample, nitrogen, hydrogen, carbon dioxide and/or other organicbyproducts. The fluid then exits urea decomposition unit 50 via inlet 54as fluid without urea or a substantially reduced amount of urea (e.g.,about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the amount ofurea prior to entering the urea decomposition cell).

The urea decomposition unit 50 is more effective in oxidizing urea whenelectrooxidation is performed at a high (basic) pH including, forexample, pH 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5,13.0, 13.5, or 14.0. For this reason, urea decomposition unit 50 can beplaced into fluid communication with an electrodialysis unit 100 that isconfigured to raise the pH level in the urea decomposition unit 50and/or to raise the pH level of the fluid passing into inlet 52 and/or52 a. In an embodiment, the pH of fluid sent to urea decomposition unit50 can be 7.1 and above, for example, from about pH 11.5 to 13.5,preferably from about pH 12.0 to 13.0.

In the embodiment illustrated in FIG. 1, urea decomposition unit 50 isin fluid communication with an electrodialysis unit 100, as illustratedin more detail in FIG. 3. Electrodialysis unit 100 is a two-compartmentelectrodialysis unit including an anode 102 and a cathode 104 forseparation of a salt solution via electrodialysis to generate an acidstream and a basic stream. A first compartment 106 is located between afirst ion exchange membrane 110 and a bipolar membrane (“BPM”) 112 andhas an inlet 106 a and an outlet 106 b. A second compartment 108 islocated between bipolar membrane 112 and a second ion exchange membrane114 and has an inlet 108 a and an outlet 108 b. The cathode 104 islocated on the opposite side of first ion exchange membrane 110 fromfirst compartment 106, and the anode 102 is located on the opposite sideof second ion exchange membrane 114 from second compartment 108. Acathode compartment 126 is located between cathode 104 and first ionexchange membrane 110 and has an inlet 126 a and an outlet 126 b. Ananode compartment 128 is located between anode 102 and second ionexchange membrane 114 and has an inlet 128 a and an outlet 128 b. In theillustrated embodiment, the first ion exchange membrane 110 is an anionexchange membrane (“AEM”) 110, and the second ion exchange membrane 114is a cation exchange membrane (“CEM”) 114. In a further embodiment, anelectrodialysis unit may comprise repeats of the above-describedtwo-compartment electrodialysis unit (i.e., [two-compartmentelectrodialysis unit]_(n), where n can be any integer).

A power source 132 can create a potential difference between the anode102 and cathode 104. The power source 132 provides an electricalpotential to split water in bipolar membrane 112 into H⁺ and OH⁻.

Bipolar membrane 112 includes a cation exchange membrane (“CEM”) 120 andan anion exchange membrane (“AEM”) 122. Water can be fed into a watercompartment 130 between CEM 120 and AEM 122 from a source of water (notshown). When a potential difference (e.g., a potential differencesufficient to split water) is created between the anode 102 and cathode104, the potential difference causes water between CEM 120 and AEM 122to split into positively charged ions (H+) and negatively charged ions(OH−) and flow through CEM 120 and AEM 122 into the first compartment106 and second compartment 108, respectively. Specifically, positivelycharged ions (H+) flow through CEM 120 into first compartment 106 asillustrated by arrow 132, while negatively charged ions (OH−) flowthrough AEM 122 into second compartment 108 as illustrated by arrow 134.AEM 110 prevents the positively charged ions (H+) from flowing out offirst compartment 106 as illustrated by arrow 136, while CEM 114prevents the negatively charged ions (OH−) from flowing out of secondcompartment 108 as illustrated by arrow 138.

A salt solution can be passed through cathode compartment 126 betweencathode 104 and AEM 110, and through anode compartment 128 between anode102 and CEM 114. In the illustrated example, the salt solution islabeled as MX. As the salt solution MX passes through cathodecompartment 126 between cathode 104 and AEM 110, the potentialdifference (e.g., a potential difference sufficient to split the salt MXinto M+ and X−) created between anode 102 and cathode 104 drivesnegatively charged ions (X−) through AEM 110 (toward the anode) and intofirst compartment 106, as illustrated by arrow 140. Similarly, as thesalt solution MX passes through anode compartment 128 between anode 106and CEM 114, the potential difference between anode 102 and cathode 104drives positively charged ions (M+) through second ion exchange membrane114 (toward the cathode) and into second compartment 108, as illustratedby arrow 142. CEM 120 prevents the negatively charged ions (X−) fromflowing out of first compartment 106 (and into the second compartment108) as illustrated by arrow 144, while AEM 122 prevents the positivelycharged ions (M+) from flowing out of second compartment 108 (and intothe first compartment 106) as illustrated by arrow 146.

The potential difference created between the anode 102 and the cathode104 is preferably sufficient to split water into positively charged ions(H+) and negatively charged ions (OH−) and split a salt MX into M+ andX−.

The potential difference created between anode 102 and cathode 104therefore causes positively charged ions (H+) to flow through CEM 120into first compartment 106 and causes negatively charged ions (X−) toflow through AEM 110 and into first compartment 106. The H+ and X− ionsthen combine in first compartment 106 to create an acidic solution (HX)with a low pH. Similarly, the potential difference created between anode102 and cathode 104 causes negatively charged ions (OH−) flow throughAEM 122 into second compartment 108 and causes positively charged ions(M+) to flow through CEM 114 and into second compartment 108. The M+ andOH− ions then combine in the second compartment 108 to create a basicsolution (MOH) with a high pH.

In one example, the salt solution (MX) is sodium chloride (NaCl) (i.e.,M=Na, X=Cl). The potential difference created between anode 102 andcathode 104 causes negatively charged ions (Cl−) to flow through AEM 110and into first compartment 106, and causes positively charged ions (Na+)to flow through CEM 114 and into second compartment 108. The H+ and Cl−ions combine in first compartment 106 to create HCl, which lowers the pHof any liquid in first compartment 106. The Na+ and OH− ions combine insecond compartment 108 to create NaOH. In other embodiment, the saltsolution can include one or more salts selected from the groupconsisting of: a sodium salt, a magnesium salt, a calcium salt, lactate,carbonate, acetate, citrate, and phosphate. In another embodiment,source 150 can include used dialysis fluid/renal therapy solution thatis in need of regeneration for further renal failure therapy.

Returning to FIG. 1, an example device 10 is illustrated to show howurea decomposition unit 50 can be placed in fluid communication withelectrodialysis unit 100. First, a source of salt solution 150(represented in FIG. 1 by “MX”) containing urea can be placed in fluidcommunication with one or more of first compartment 106, secondcompartment 108, cathode compartment 126 and/or anode compartment 128.In the illustrated embodiment, the source of fluid 150 is placed intofluid communication with the respective inlets 126 a, 106 a and 108 a ofcathode compartment 126, first compartment 106 and second compartment108, as illustrated by flowpaths (arrows) 152, 154 and 156. Asillustrated by flowpath (arrow) 158, the salt solution that flows intocathode compartment 126 loses negatively charged ions (X−) to firstcompartment 106 and is then circulated to anode compartment 128, whereit loses positively charged ions (M+) to second compartment 108. Asillustrated by flowpath (arrow) 160, the salt solution circulatedthrough cathode compartment 126 and anode compartment 128 can then besent to drain 164 as waste fluid.

Referring to FIGS. 1 and 3, the salt solution (MX) that flows from inlet106 a to outlet 106 b of first compartment 106 is combined with the acidsolution (HX) that has been formed in first compartment 106 as describedabove, which lowers the pH of the salt solution (MX) flowing throughfirst compartment 106. Likewise, the salt solution (MX) that flows frominlet 108 a to outlet 108 b of second compartment 108 is combined withthe base solution (MOH) that has been formed in second compartment 108as described above, which increases the pH of the salt solution (MX)flowing through second compartment 108. Electrodialysis unit 100therefore produces an outflow of an acidic salt solution (represented atflowpath 166 leaving outlet 106 b) and an outflow of a base saltsolution (represented at flowpath 168 leaving outlet 108 b).

As illustrated by flowpath 170, a large portion of the originalurea-containing salt solution (MX) can be sent directly to ureadecomposition unit 50 without passing through electrodialysis unit 100.In the illustrated embodiment, approximately 94% of the salt solutionflows directly to urea decomposition unit 50 without passing throughelectrodialysis unit 100. The original salt solution (MX) is combinedwith the base solution (MOH) created by electrodialysis unit 100(illustrated by flowpath 168) to raise the pH of the combined saltsolution entering inlet 52 of urea decomposition unit 50. As explainedabove, it has been demonstrated that urea decomposition unit 50 is moreeffective in oxidizing urea when fluid entering inlet 52 is basic(alkaline) as opposed to acidic. In one embodiment, the base solution(MOH) flowing through flowpath 168 can mix with original salt solutionflowing through flowpath 170 before the mixed salt solution flows intoinlet 52 of urea decomposition unit 50. In another embodiment, the basesolution (MOH) flowing through flowpath 168 can flow into a separateinlet 52 a of urea decomposition unit 50 through flowpath 174 and mixwith original salt solution that has already flowed through inlet 52.

After the combined salt solution has been cleansed of urea, the outflowof acidic solution (represented at flowpath 166) is added to the outflowof combined solution from outlet 54 (represented at flowpath 172) ofurea decomposition unit 50 so that the pH of the combined salt solutionafter intersection of flowpaths 166 and 172 is lowered back to normal(e.g. a physiological pH such as a pH of about 7.0). The combinedsolution can then be sent to a dialysis fluid equalization unit 28, asdescribed below. The low pH acidic solution (HX) can also be used toclean the cells in the urea decomposition unit 50 and/or electrodialysisunit 100 after operation.

In use, the majority of salt solution from source 150 is output fromsource 150 at flowpath 170. In an embodiment, the source of saltsolution 150 outputs about 405 mL/min of salt solution. 380 mL/min isdirected to urea decomposition unit 50 along flowpath 170, 5 mL/min isdirected to cathode compartment 126 and anode compartment 128 alongflowpaths 152, 158 and 160, 10 mL/min is directed through firstcompartment 106 along flowpath 154, and 10 mL/min is directed throughsecond compartment 108 along flowpath 156. Thus, 96% of the saltsolution entering urea decomposition unit 50 via flowpaths 168 and 170,and 97.5% of the cleansed solution after the combination of flowpaths166 and 172, is cleansed of urea via electrooxidation.

It is preferable to keep the amount of fluid sent to electrodialysisunit 100 as low as possible, because less fluid is oxidized of urea byurea decomposition unit 50 as more fluid is sent to cathode compartment126 and first compartment 106. In an embodiment, approximately 70 to 95%of the total solution from source 150 passes along flowpath 170 directlyto urea decomposition unit 50, while the remaining 5 to 30% of the totalsolution from source 150 passes along flowpaths 152, 154 and 156 toelectrodialysis unit 100. In another embodiment, the source of saltsolution 150 outputs about 100 to 600 mL/min of salt solution. 70% to100% of the salt solution is directed to urea decomposition unit 50along flowpath 170, and 0% to 30% of the total solution from source 150passes along flowpaths 152, 154 and 156 to electrodialysis unit 100.

In another embodiment, source 150 contains sodium chloride (NaCl) at0.132 mol/L (pH 7.0) and outputs about 400 mL/min of solution. 30 mL/minflows through cathode compartment 126 and anode compartment 128 alongflowpaths 152, 158 and 160. 5 mL/min flows through first compartment 106along flowpath 154, which causes first compartment 106 to outputsolution with 0.792 mol/L of HCL (pH 0.1) at flowpath 166. 5 mL/min alsoflows through second compartment 108 along flowpath 156, which causessecond compartment 108 to output solution with 0.792 mol/L of NaOH (pH13.9) at flowpath 168. The remaining 360 mL/min from the total 400mL/min output by source 150 is directed along flowpath 170. Whenflowpaths 170 and 168 combine, the combined solution has an NaOHconcentration of 0.0108 mol/L (ph 12.04) as it enters inlet 52 of ureadecomposition unit 50.

In an embodiment, dialysis fluid with salt solution (NaCl) achieves a pHof about 13.1 at urea decomposition unit 50 (0.132 mol/L NaCl convertedinto 0.132 mol/L NaOH=pH 13.1). A pH of 13.1 is a best case scenario fordialysis fluid solution in which 100% of the dialysis fluid solution issent directly to the electrodialysis unit 100, and then the basic feedis sent to the urea decomposition unit 50.

FIG. 1 illustrates that in an embodiment, device 10 may include one ormore pump 178, and a plurality of valves 180, 182, 184, 186, 188, 190that control fluid flow along the respective flowpaths. Pump 178 may bea peristaltic pump or a volume membrane pump. The valves 180, 182, 184,186, 188, 190 may be variable fluid orifice valves that allow apercentage of fluid to flow through each respective flowpath.Alternatively, the valves can be solenoid valves or other valves knownto those of ordinary skill in the art. In the illustrated embodiment,the valves 180, 182, 184, 186, 188, 190 are electrically connected to acontroller 194. The controller 194 may include one or more processor andmemory programmed to control one or more pump 178 and the variableorifice size of valves 180, 182, 184, 186, 188, 190 to achieve the flowrates and percentages discussed above or to achieve other flowrates andpercentages through the respective flowpaths.

In an embodiment, any one or more or all of valves 180, 182, 184, 186,188, 190 may alternatively be solenoid valves that operate withcontroller 194 so that they are opened a specified amount of time toachieve the flow distributions through device 10 described above. In afurther embodiment, one or more valves, such as valves 180, 182, 184,186, 188, 190, may be replaced with a balance chamber that operates withits own valves. Each balance chamber may include a first compartment anda second compartment separated by a flexible membrane. When a firstinlet solenoid valve opens to allow the first compartment to fill withfluid, the flexible membrane is pushed into the second compartment toexpel like fluid from the second compartment through an opened secondoutlet solenoid valve. When a second inlet solenoid valve opens to allowthe second compartment to fill with fluid, the flexible membrane ispushed into the first compartment to expel like fluid from the firstcompartment through an opened first outlet solenoid valve. Because thevolume of the first and second compartments is known, controller 194 canprecisely meter fluid through the flowpaths by toggling the solenoidvalves of the balance chamber between the first compartment and thesecond compartment and control flow rate by controlling how often theinlet and outlet valves are cycled.

In an embodiment, device 10 includes a pH sensor 196 that ensures the pHof the cleansed salt solution is at or near 7.0 (i.e., neutral). The pHsensor 196 may provide feedback to controller 194, so that controller194 controls pump 178 and/or valves 180, 182, 184, 186, 188, 190 toraise or lower the pH of the outflow as necessary. Device 10 may alsoinclude one or more flowmeters (FM) 198 to monitor flow at any desiredone or more location within the respective flowpaths of device 10 andprovide flowrate feedback to controller 194.

FIG. 4 illustrates an example embodiment of another electrodialysis unit200 that can be combined with urea decomposition unit 50 to cleanse asalt solution of urea. Electrodialysis unit 200 is a three-compartmentelectrodialysis unit including an anode 202 and a cathode 204 forseparation of a salt solution via electrodialysis. Similar to above,electrodialysis unit 200 includes an anode compartment 206 locatedbetween anode 202 and a bipolar membrane 216 and including an inlet 206a and an outlet 206 b, a first compartment 208 located between bipolarmembrane 216 and a first ion exchange membrane 218 (here AEM 218) andincluding an inlet 208 a and an outlet 208 b, a second compartment 210located between AEM 218 and a second ion exchange membrane 220 (here CEM220) and including an inlet 210 a and an outlet 210 b, a thirdcompartment 212 located between CEM 220 and a bipolar membrane 222 andincluding an inlet 212 a and an outlet 212 b, and a cathode compartment214 located between bipolar membrane 222 and cathode 204 and includingan inlet 214 a and an outlet 214 b. In a further embodiment, anelectrodialysis unit may comprise repeats of the above-describedthree-compartment electrodialysis unit (i.e., [three-compartmentelectrodialysis unit]_(n), where n can be any integer).

A power source 232 can create a potential difference between the anode202 and cathode 204. The power source 232 provides an electricalpotential to split water in bipolar membranes 216 and 222 into H⁺ andOH⁻.

Bipolar membranes 216 and 222 each include a CEM and an AEM as describedabove with respect to bipolar membrane 112. For each bipolar membrane216 and 222, water can be fed into a water compartment between the CEMand AEM from a source of water. For simplicity, the water compartment,CEM and AEM are not shown separately in FIG. 4. When a potentialdifference (e.g., a potential difference sufficient to split water) iscreated between the anode 202 and cathode 204, the potential differencecauses water to split into positively charged ions (H+) and negativelycharged ions (OH−) in bipolar membrane 216. The generated negativelycharged ions (OH−) from bipolar membrane 216 flow through the AEM andinto cathode compartment 206, and the generated positively charged ions(H+) flow through the CEM and into first compartment 208. Similarly, thepotential difference causes the negatively charged ions (OH−) generatedin the bipolar membrane 222 to flow through the AEM and into thirdcompartment 212, and the positively charged ions (H+) to flow throughthe CEM and into cathode compartment 214.

FIG. 5 shows a device 12 placing electrodialysis unit 200 in fluidcommunication with the urea decomposition unit 50 of FIG. 2. As shown byflowpaths 252, 254 and 256, salt solution (MX) from a source 250 can bepassed through anode compartment 206 and cathode compartment 214 andsent to drain 248 as described above. The salt solution can also bepassed through each of first compartment 208 (flowpath 258), secondcompartment 210 (flowpath 260) and third compartment 212 (flowpath 262).As salt solution passes through second compartment 210, the potentialdifference created between the anode 202 and cathode 204 drivesnegatively charged ions (X−) through AEM 218 and into first compartment208. Likewise, the potential difference created between the anode 202and cathode 204 drives positively charged ions (M+) through CEM 220 andinto third compartment 212. The CEM of bipolar membrane 216 prevents thenegatively charged ions (X−) from flowing out of first compartment 208,while the AEM of bipolar membrane 222 prevents the positively chargedions (M+) from flowing out of third compartment 212.

The potential difference created between anode 202 and cathode 204therefore causes positively charged ions (H+) and negatively chargedions (X−) in first compartment 208 to create an acidic solution (HX)with a low pH. Similarly, the potential difference created between anode202 and cathode 204 causes negatively charged ions (OH−) and positivelycharged ions (M+) in third compartment 212 to create a basic solution(MOH) with a high pH.

Similar to above, flowpaths 266 and 268 illustrate that ureadecomposition unit 50 can be placed in fluid communication withelectrodialysis unit 200 so that the high pH basic solution (MOH) can becombined with an original salt solution 250 containing urea to raise thepH of the original salt solution prior to entering urea decompositionunit 50. In one embodiment, the basic solution (MOH) flowing throughflowpath 266 can mix with original salt solution flowing throughflowpath 268 before the mixed salt solution flows into inlet 52 of ureadecomposition unit 50. In another embodiment, the base solution (MOH)flowing through flowpath 266 can flow into a separate inlet 52 a of ureadecomposition unit 50 through flowpath 274 and mix with original saltsolution that has already flowed through inlet 52.

The low pH acidic solution (HX) can then be combined with outflow fromurea decomposition unit 50 so that the pH of the combined salt solutionis lowered back to normal (e.g., a physiological pH such as a pH ofabout 7.0), as illustrated by flowpath 270. The combined solution canthen be sent to a dialysis fluid equalization unit 28, as describedbelow. The low pH acidic solution (HX) can also be used to clean thecells in the urea decomposition unit 50 and/or electrodialysis unit 200after operation.

In an embodiment, approximately 70 to 90% of the total solution fromsource 250 passes along flowpath 268 directly to urea decomposition unit50, while the remaining 10 to 30% of the total solution from source 250passes along flowpaths 252, 258, 260 and 262 to electrodialysis unit200.

FIG. 5 illustrates that in an embodiment, device 12 may include one ormore pump 278, and a plurality of valves 280, 282, 284, 286, 288, 290,292 that control fluid flow along the respective flowpaths. Pump 278 maybe a peristaltic pump or a volume membrane pump. The valves 280, 282,284, 286, 288, 290, 292 may be variable fluid orifice valves that allowa percentage of fluid to flow through each respective flowpath.Alternatively, the valves can be solenoid valves or other valves knownto those of ordinary skill in the art. In the illustrated embodiment,the valves 280, 282, 284, 286, 288, 290, 292 are electrically connectedto a controller 294. The controller 294 may include one or moreprocessor and memory programmed to control one or more pump 278 and thevariable orifice size of valves 280, 282, 284, 286, 288, 290, 292 toachieve the flow rates and percentages discussed above or to achieveother flowrates and percentages through the respective flowpaths.

In an embodiment, any one or more or all of valves 280, 282, 284, 286,288, 290, 292 may alternatively be solenoid valves that operate withcontroller 294 so that they are opened a specified amount of time toachieve the flow distributions through device 12 described above. In afurther embodiment, one or more valves, such as valves 280, 282, 284,286, 288, 290, 292, may be replaced with a balance chamber that operateswith its own valves Each balance chamber may include a first compartmentand a second compartment separated by a flexible membrane. When a firstinlet solenoid valve opens to allow the first compartment to fill withfluid, the flexible membrane is pushed into the second compartment toexpel like fluid from the second compartment through an opened secondoutlet solenoid valve. When a second inlet solenoid valve opens to allowthe second compartment to fill with fluid, the flexible membrane ispushed into the first compartment to expel like fluid from the firstcompartment through an opened first outlet solenoid valve. Because thevolume of the first and second compartments is known, controller 294 canprecisely meter fluid through the flowpaths by toggling the solenoidvalves of the balance chamber between the first compartment and thesecond compartment and control flow rate by controlling how often theinlet and outlet valves are cycled.

In an embodiment, device 12 includes a pH sensor 296 that ensures the pHof the cleansed salt solution is at or near 7.0 (i.e., neutral). The pHsensor 296 may provide feedback to controller 294, so that controller294 controls pump 278 and/or valves 280, 282, 284, 286, 288, 290, 292 toraise or lower the pH of the outflow as necessary. Device 12 may alsoinclude one or more flowmeters (FM) 298 to monitor flow at any desiredone or more location within the respective flowpaths of device 12 andprovide flowrate feedback to controller 294.

FIG. 6 illustrates an embodiment of another electrodialysis unit 300that can be combined with urea decomposition unit 50 to cleanse a saltsolution of urea. Electrodialysis unit 300 is a two-compartment,two-cell electrodialysis unit including an anode 302 and a cathode 304for separation of a salt solution via electrodialysis. Similar to above,electrodialysis unit 300 includes an anode compartment 306 locatedbetween anode 302 and a first ion exchange membrane 318 and including aninlet 306 a and an outlet 306 b, a first compartment 308 located betweenfirst ion exchange membrane 318 and a bipolar membrane 320 and includingan inlet 308 a and an outlet 308 b, a second compartment 310 locatedbetween bipolar membrane 320 and a second ion exchange membrane 322 andincluding an inlet 310 a and an outlet 310 b, a third compartment 312located between second ion exchange membrane 322 and a bipolar membrane324 and including an inlet 312 a and an outlet 312 b, a fourthcompartment 314 located between bipolar membrane 324 and a third ionexchange membrane 326 and including an inlet 314 a and an outlet 314 b,and a cathode compartment 316 located between third ion exchangemembrane 326 and cathode 304 and including an inlet 316 a and an outlet316 b. In the illustrated embodiment, the first ion exchange membrane318, second ion exchange membrane 322 and third ion exchange membrane326 are each a CEM.

A power source 332 can create a potential difference between the anode302 and cathode 304. The power source 332 provides an electricalpotential to split water in bipolar membranes 320 and 324 into H⁺ andOH⁻.

Bipolar membranes 320 and 324 each include a CEM and an AEM as describedabove with respect to bipolar membrane 112. For each bipolar membrane320 and 324, water can be fed into a water compartment between the CEMand AEM from a source of water. For simplicity, the water compartment,CEM and AEM are not shown separately in FIG. 6. When a potentialdifference (e.g., a potential difference sufficient to split water) iscreated between the anode 302 and cathode 304, the potential differencecauses water to split into positively charged ions (H+) and negativelycharged ions (OH−). The generated negatively charged ions (OH−) frombipolar membrane 320 flow through the AEM and into first compartment308, and the generated positively charged ions (H+) flow through the CEMand into second compartment 310. Similarly, the potential differencecauses the negatively charged ions (OH−) from bipolar membrane 324 toflow through the AEM and into third compartment 312, and causes thepositively charged ions (H+) to flow through the CEM and into fourthcompartment 314.

FIG. 7 shows a device 14 placing electrodialysis unit 300 in fluidcommunication with the urea decomposition unit 50 of FIG. 2. As shown byflowpaths 352, 354 and 356, salt solution (MX) from a source 350 can bepassed through anode compartment 306 and cathode compartment 316 andsent to drain 348 as described above. A salt solution can also be passedthrough each of first compartment 308 (flowpath 358), second compartment310 (flowpath 360), third compartment 312 (flowpath 362) and fourthcompartment 314 (flowpath 364). In the illustrated embodiment, first ionexchange membrane 318 is a first CEM 318, second ion exchange membrane322 is a second CEM 322, and third ion exchange membrane 326 is a thirdCEM 326. Salt solution (MX) passing through anode compartment 306therefore loses positively charged ions (M+) through CEM 318 to firstcompartment 308, salt solution passing through second compartment 310loses positively charged ions (M+) through CEM 322 to third compartment312, and salt solution passing through fourth compartment 314 losespositively charged ions (M+) through CEM 326 to cathode compartment 316.The AEM of bipolar membrane 320 prevents the positively charged ions(M+) from flowing out of first compartment 308, while the AEM of bipolarmembrane 324 prevents the positively charged ions (M+) from flowing outof third compartment 312.

The potential difference created between anode 302 and cathode 304causes negatively charged ions (OH−) and positively charged ions (M+) toform a basic solution (MOH) with a high pH in first compartment 308 andthird compartment 312. Similar to above, flowpaths 368 and 370illustrate that urea decomposition unit 50 can be placed in fluidcommunication with electrodialysis unit 300 so that the high pH basicsolution (MOH) from first compartment 308 and third compartment 312 canbe combined with original salt solution containing urea to raise the pHof the original salt solution prior to entering urea decomposition unit50. In one embodiment, the basic solution (MOH) flowing through flowpath370 can mix with original salt solution flowing through flowpath 368before the mixed salt solution flows into inlet 52 of urea decompositionunit 50. In another embodiment, the base solution (MOH) flowing throughflowpath 370 can flow into a separate inlet 52 a of urea decompositionunit 50 through flowpath 374 and mix with original salt solution thathas already flowed through inlet 52.

Low pH acidic solution can then be combined with outflow from ureadecomposition unit 50 so that the pH of the combined salt solution islowered back to normal, as illustrated by flowpath 372. The combinedsolution can then be sent to a dialysis fluid equalization unit 28, asdescribed below. The low pH acidic solution can also be used to cleanthe cells in the urea decomposition unit 50 and/or electrodialysis unit300 after operation.

In an embodiment, approximately 70 to 95% of the total solution fromsource 350 passes along flowpath 368 directly to urea decomposition unit50, while the remaining 5 to 30% of the total solution from source 350passes along flowpaths 352, 360, 362, 364 and 366 to electrodialysisunit 300.

FIG. 7 illustrates that in an embodiment, device 14 may include one ormore pumps 378, and a plurality of valves 380, 382, 384, 386, 388, 390,392, 393 that control fluid flow along the respective flowpaths. Pump378 may be a peristaltic pump or a volume membrane pump. The valves 380,382, 384, 386, 388, 390, 392, 393 may be variable fluid orifice valvesthat allow a percentage of fluid to flow through each respectiveflowpath. Alternatively, the valves can be solenoid valves or othervalves known to those of ordinary skill in the art. In the illustratedembodiment, the valves 380, 382, 384, 386, 388, 390, 392, 393 areelectrically connected to a controller 394. The controller 394 mayinclude one or more processor and memory programmed to control one ormore pump 378 and the variable orifice size of valves 380, 382, 384,386, 388, 390, 392, 393 to achieve the flow rates and percentagesdiscussed above or to achieve other flowrates and percentages throughthe respective flowpaths.

In an embodiment, any one or more or all of valves 380, 382, 384, 386,388, 390, 392, 393 may alternatively be solenoid valves that operatewith controller 394 so that they are opened a specified amount of timeto achieve the flow distributions through device 14 described above. Ina further embodiment, one or more valves, such as valves 380, 382, 384,386, 388, 390, 392, 393, may be replaced with a balance chamber thatoperates with its own valves. Each balance chamber may include a firstcompartment and a second compartment separated by a flexible membrane.When a first inlet solenoid valve opens to allow the first compartmentto fill with fluid, the flexible membrane is pushed into the secondcompartment to expel like fluid from the second compartment through anopened second outlet solenoid valve. When a second inlet solenoid valveopens to allow the second compartment to fill with fluid, the flexiblemembrane is pushed into the first compartment to expel like fluid fromthe first compartment through an opened first outlet solenoid valve.Because the volume of the first and second compartments is known,controller 394 can precisely meter fluid through the flowpaths bytoggling the solenoid valves of the balance chamber between the firstcompartment and the second compartment and control flow rate bycontrolling how often the inlet and outlet valves are cycled.

In an embodiment, device 14 includes a pH sensor 396 that ensures the pHof the cleansed salt solution is at or near 7.0 (i.e., neutral). The pHsensor 396 may provide feedback to controller 394, so that controller394 controls pump 378 and/or valves 380, 382, 384, 386, 388, 390, 392,393 to raise or lower the pH of the outflow as necessary. Device 14 mayalso include one or more flowmeters (FM) 398 to monitor flow at anydesired one or more location within the respective flowpaths of device14 and provide flowrate feedback to controller 394.

FIG. 8 illustrates a device 400 that combines the urea decomposition andelectrodialysis units discussed above into the same unit. Morespecifically, device 400 take the electrodes from urea decompositionunit 50 and places the electrodes inside of one or more compartment ofelectrodialysis unit 100, 200, 300. The oxidation of urea from saltsolution therefore occurs inside of the compartment due to theelectrocatalytic surfaces of the electrodes for decomposition of ureavia electrooxidation.

Similar to above, device 400 includes a cathode compartment 406 locatedbetween a cathode 404 and a first ion exchange membrane 414 (here AEM414) and including an inlet 406 a and an outlet 406 b, a firstcompartment 408 located between AEM 414 and a bipolar membrane 416 andincluding an inlet 408 a and an outlet 408 b, a second compartment 410located between bipolar membrane 416 and a second ion exchange membrane418 (here CEM 418) and including an inlet 410 a and an outlet 410 b, andan anode compartment 212 located between CEM 418 and cathode 404 andincluding an inlet 412 a and an outlet 414 b. Device 400 may include anyone, or more, or all of the controllers, valves, pH sensors, and/orflowmeters described herein.

Second compartment 410 of a device 400 also includes an electrooxidationcell 450 with one or more sets of electrodes 440 with electrocatalyticsurfaces for the decomposition of urea via electrooxidation. Each set ofelectrodes can include an anode and a cathode. In an embodiment, theelectrodes 440 include a cathode and an anode, and the anodes comprise atransition metal and/or mixtures thereof and/or alloys thereof. Thetransition metal can be selected from the group consisting of cobalt,copper, iron, nickel, platinum, palladium, iridium, ruthenium, andrhodium. In an embodiment, the cathode can include platinum and theanode comprises wherein the anode comprises nickel, nickel oxide, nickelhydroxide or nickel oxide hydroxide (NiOOH). The electrooxidation cell450 can also include an alkaline polymeric gel.

A power source 442 provides the electrodes 440 with an electricalcharge, and a power source 444 can be used to create a potentialdifference between the anode 402 and cathode 404. Alternatively, powersource 442 and power source 444 can be the same power source. The powersource 442 provides the electrodes 440 with an electrical charge toactivate an electrocatalytic surface of the electrodes. The voltagedifference applied across the electrodes (e.g. cathode and anode) can besufficient to produce nitrogen gas, carbon dioxide gas, and water. Thepower source 444 provides an electrical charge to split water in bipolarmembrane 416 into H⁺ and OH⁻.

Bipolar membrane 416 includes a CEM 420 and an AEM 422. Water can be fedinto a water compartment 424 between CEM 420 and AEM 422 from a sourceof water (not shown). When a potential difference (e.g., a potentialdifference sufficient to split water) is created between the anode 402and cathode 404, the potential difference causes water to split intopositively charged ions (H+) and negatively charged ions (OH−), and thepositively and negatively charged ions generated between CEM 420 and AEM422 flow through CEM 420 and AEM 422 into the first compartment 408 andsecond compartment 410, respectively. Specifically, positively chargedions (H+) flow through CEM 420 into first compartment 408 as illustratedby arrow 432, while negatively charged ions (OH−) flow through AEM 422into second compartment 410 as illustrated by arrow 434. AEM 414prevents the positively charged ions (H+) from flowing out of firstcompartment 408, while CEM 418 prevents the negatively charged ions(OH−) from flowing out of second compartment 410.

FIG. 9 shows the flow paths of fluid through device 400. As shown byflowpaths 452, 454 and 456, salt solution (MX) from a source 450 can bepassed through anode compartment 406 and cathode compartment 412 andsent to drain 448 as described above. The salt solution (MX) can also bepassed through each of first compartment 408 (flowpath 458) and secondcompartment 410 (flowpath 460). As salt solution (MX) passes throughfirst compartment 408, the salt solution becomes more acidic asnegatively charged ions (X−) from cathode compartment 406 combine withpositively charged ions (H+) from bipolar membrane 416. As salt solution(MX) passes through second compartment 410, the salt solution becomesmore basic (alkaline) as positively charged ions (M+) from anodecompartment 412 combine with negatively charged ions (OH−) from bipolarmembrane 416.

The one or more sets (e.g., [set of electrodes]_(n), where n can be anyinteger) of electrodes 440 with electrocatalytic surfaces ofelectrooxidation cell 450 are located within second compartment 410because the salt solution (MX) within second compartment 410 becomesmore basic (alkaline) as positively charged ions (M+) from anodecompartment 412 combine with negatively charged ions (OH−) from bipolarmembrane 416. As explained above, it has been determined that a morebasic alkaline solution is better for the decomposition of urea viaelectrooxidation. The urea cleansed salt solution can then be combinedwith the acidic solution from first compartment 408, as indicated byflowpath 462, to neutralize the overall pH of the combined solutionoutput by device 400.

In use, second compartment 410 can receive much more solution than firstcompartment 408, so that the majority of salt solution output atflowpath 462 is cleansed of urea via electrooxidation. In an embodiment,the source of salt solution 450 outputs about 405 mL/min of saltsolution. 5 mL/min is directed to anode compartment 406 and cathodecompartment 412 along flowpaths 452, 454 and 456, 10 mL/min is directedto first compartment 408 along flowpath 458, and the other 390 mL/min isdirected to second compartment 410 along flowpath 460. Thus, 96% of thesalt solution leaving source 450, and 97.5% of the cleansed solutionleaving device 400 at flowpath 462, is cleansed of urea viaelectrooxidation.

FIG. 9 illustrates that in an embodiment, device 400 may include one ormore pump 478, and a plurality of valves 480, 482, 484 that controlfluid flow along the respective flowpaths. Pump 478 may be a peristalticpump or a volume membrane pump. The valves 480, 482, 484 may be variablefluid orifice valves that allow a percentage of fluid to flow througheach respective flowpath. Alternatively, the valves can be solenoidvalves or other valves known to those of ordinary skill in the art. Inthe illustrated embodiment, the valves 480, 482, 484 are electricallyconnected to a controller 494. The controller 494 may include one ormore processor and memory programmed to control one or more pump 478 andthe variable orifice size of valves 480, 482, 484 to achieve the flowrates and percentages discussed above or to achieve other flowrates andpercentages through the respective flowpaths.

In an embodiment, any one or more or all of valves 480, 482, 484 mayalternatively be solenoid valves that operate with controller 494 sothat they are opened a specified amount of time to achieve the flowdistributions through device 400 described above. In a furtherembodiment, one or more valves, such as valves 480, 482, 484, may bereplaced with a balance chamber that operates with its own valves. Eachbalance chamber may include a first compartment and a second compartmentseparated by a flexible membrane. When a first inlet solenoid valveopens to allow the first compartment to fill with fluid, the flexiblemembrane is pushed into the second compartment to expel like fluid fromthe second compartment through an opened second outlet solenoid valve.When a second inlet solenoid valve opens to allow the second compartmentto fill with fluid, the flexible membrane is pushed into the firstcompartment to expel like fluid from the first compartment through anopened first outlet solenoid valve. Because the volume of the first andsecond compartments is known, controller 494 can precisely meter fluidthrough the flowpaths by toggling the solenoid valves of the balancechamber between the first compartment and the second compartment andcontrol flow rate by controlling how often the inlet and outlet valvesare cycled.

In an embodiment, device 400 includes a pH sensor 496 that ensures thepH of the cleansed salt solution is at or near 7.0 (i.e., neutral). ThepH sensor 496 may provide feedback to controller 494, so that controller494 controls pump 478 and/or valves 480, 482, 484 to raise or lower thepH of the outflow as necessary. Device 400 may also include one or moreflowmeters (FM) 498 to monitor flow at any desired one or more locationwithin the respective flowpaths of device 400 and provide flowratefeedback to controller 494.

FIG. 10 illustrates a device 500 that combines the urea decompositionand electrodialysis units discussed above into the same unit. Morespecifically, device 500 takes the electrodes from urea decompositionunit 50 and places the electrodes inside of one or more compartment ofelectrodialysis unit 200. The oxidation of urea from salt solutiontherefore occurs inside of the compartment due to the electrocatalyticsurfaces of the electrodes for decomposition of urea viaelectrooxidation. Device 500 may be used with any of the controllers,valves, pH sensors, and/or flowmeters described herein.

Similar to above, device 500 is a three-compartment electrodialysis unitincluding an anode 502 and a cathode 504 for separation of a saltsolution via electrodialysis. Device 500 includes an anode compartment506 located between anode 502 and a bipolar membrane 516 and includingan inlet 506 a and an outlet 506 b, a first compartment 508 locatedbetween bipolar membrane 516 and a first ion exchange membrane 518 (hereAEM 518) and including an inlet 508 a and an outlet 508 b, a secondcompartment 510 located between AEM 518 and a second ion exchangemembrane 520 (here CEM 520) and including an inlet 510 a and an outlet510 b, a third compartment 512 located between CEM 520 and a bipolarmembrane 522 and including an inlet 512 a and an outlet 512 b, and acathode compartment 514 located between bipolar membrane 522 and cathode504 and including an inlet 514 a and an outlet 514 b. In a furtherembodiment, an electrodialysis unit may comprise repeats of theabove-described three-compartment electrodialysis unit (i.e.,[three-compartment electrodialysis unit]_(n), where n can be anyinteger).

Third compartment 512 of device 5000 also includes an electrooxidationcell 550 with one or more sets of electrodes with electrocatalyticsurfaces for the decomposition of urea via electrooxidation. Asdiscussed above, each set of electrodes can include an anode and acathode. In an embodiment, the electrodes include a cathode and ananode, and the anodes comprise a transition metal and/or mixturesthereof and/or alloys thereof. The transition metal can be selected fromthe group consisting of cobalt, copper, iron, nickel, platinum,palladium, iridium, ruthenium, and rhodium. In an embodiment, thecathode can include platinum and the anode comprises wherein the anodecomprises nickel, nickel oxide, nickel hydroxide or nickel oxidehydroxide (NiOOH). The urea electrooxidation cell 550 can also includean alkaline polymeric gel.

A power source (not shown) provides the electrodes of electrooxidationcell 550 with an electrical charge, and a power source 544 can be usedto create a potential difference between the anode 502 and cathode 504.Alternatively, the same power source can be used for electrooxidationcell 550 and to create a potential difference between the anode 502 andcathode 504. The power source (not shown) provides the electrodes ofelectrooxidation cell 550 with an electrical charge to activate anelectrocatalytic surface of the electrodes. The voltage differenceapplied across the electrodes (e.g. cathode and anode) can be sufficientto produce nitrogen gas, carbon dioxide gas, and water. The power source444 provides an electrical charge to split water in bipolar membranes516 and 522 into H⁺ and OH⁻.

Bipolar membranes 516 and 522 each include a CEM and an AEM as describedabove with respect to bipolar membrane 112. For each bipolar membrane516 and 522, water can be fed into a water compartment between the CEMand AEM from a source of water. For simplicity, the water compartment,CEM and AEM are not shown separately in FIG. 10. When a potentialdifference (e.g., a potential difference sufficient to split water) iscreated between the anode 502 and cathode 504, the potential differencecauses water to split into positively charged ions (H+) and negativelycharged ions (OH−) in bipolar membranes 516 and 522. The generatednegatively charged ions (OH−) from bipolar membrane 516 flow through theAEM and into cathode compartment 506, and the generated positivelycharged ions (H+) flow through the CEM and into first compartment 508.Similarly, the potential difference causes the negatively charged ions(OH−) generated in the bipolar membrane 522 to flow through the AEM andinto third compartment 512, and the positively charged ions (H+) to flowthrough the CEM and into cathode compartment 514.

FIG. 11 shows the flow paths of fluid through device 500. As shown byflowpaths 552, 554 and 556, salt solution (MX) from a source 551 can bepassed through anode compartment 506 and cathode compartment 514 andsent to drain 548 as described above. The salt solution can also bepassed through each of first compartment 508 (flowpath 558), secondcompartment 510 (flowpath 560) and third compartment 512 (flowpath 562).As salt solution passes through second compartment 510, the potentialdifference created between the anode 202 and cathode 204 drivesnegatively charged ions (X−) through AEM 518 and into first compartment508. Likewise, the potential difference created between the anode 502and cathode 504 drives positively charged ions (M+) through CEM 520 andinto third compartment 512. The CEM of bipolar membrane 516 prevents thenegatively charged ions (X−) from flowing out of first compartment 508,while the AEM of bipolar membrane 522 prevents the positively chargedions (M+) from flowing out of third compartment 512. The potentialdifference created between anode 502 and cathode 504 therefore causespositively charged ions (H+) and negatively charged ions (X−) in firstcompartment 508 to create an acidic solution (HX) with a low pH.Similarly, the potential difference created between anode 502 andcathode 504 causes negatively charged ions (OH−) and positively chargedions (M+) in third compartment 512 to create a basic solution (MOH) witha high pH.

The one or more sets (e.g., [set of electrodes]_(n), where n can be anyinteger) of electrodes with electrocatalytic surfaces ofelectrooxidation cell 550 are located within third compartment 512because the salt solution (MX) within third compartment 512 becomes morebasic (alkaline) as positively charged ions (M+) from second compartment510 combine with negatively charged ions (OH−) from bipolar membrane522. As explained above, it has been determined that a more basicalkaline solution is better for the decomposition of urea viaelectrooxidation. The urea cleansed salt solution from flowpath 564 canthen be combined with the acidic solution from first compartment 508 andsolution from second compartment 510, as indicated by flowpaths 566 and568, respectively, to neutralize the overall pH of the combined solutionoutput by device 500.

In use, third compartment 512 can receive much more solution than firstcompartment 508 and second compartment 510, so that the majority of saltsolution output at flowpath 570 is cleansed of urea viaelectrooxidation. In an embodiment, the source of salt solution 551outputs about 405 mL/min of salt solution. 5 mL/min is directed to anodecompartment 506 and cathode compartment 512 along flowpaths 552, 554 and556, 10 mL/min is directed to first compartment 508 along flowpath 558,10 mL/min is directed to second compartment 510 along flowpath 560, andthe other 380 mL/min is directed to third compartment 512 along flowpath562. Thus, 94% of the salt solution leaving source 551, and 95% of thecleansed solution leaving device 500 at flowpath 570, is cleansed ofurea via electrooxidation.

FIG. 11 illustrates that in an embodiment, device 500 may include one ormore pump 578, and a plurality of valves 580, 582, 584, 586 that controlfluid flow along the respective flowpaths. Pump 578 may be a peristalticpump or a volume membrane pump. The valves 580, 582, 584, 586 may bevariable fluid orifice valves that allow a percentage of fluid to flowthrough each respective flowpath. Alternatively, the valves can besolenoid valves or other valves known to those of ordinary skill in theart. In the illustrated embodiment, the valves 580, 582, 584, 586 areelectrically connected to a controller 594. The controller 594 mayinclude one or more processor and memory programmed to control one ormore pump 578 and the variable orifice size of valves 580, 582, 584, 586to achieve the flow rates and percentages discussed above or to achieveother flowrates and percentages through the respective flowpaths.

In an embodiment, any one or more or all of valves 580, 582, 584, 586may alternatively be solenoid valves that operate with controller 594 sothat they are opened a specified amount of time to achieve the flowdistributions through device 500 described above. In a furtherembodiment, one or more valves, such as valves 580, 582, 584, 586, maybe replaced with a balance chamber that operates with its own valves.Each balance chamber may include a first compartment and a secondcompartment separated by a flexible membrane. When a first inletsolenoid valve opens to allow the first compartment to fill with fluid,the flexible membrane is pushed into the second compartment to expellike fluid from the second compartment through an opened second outletsolenoid valve. When a second inlet solenoid valve opens to allow thesecond compartment to fill with fluid, the flexible membrane is pushedinto the first compartment to expel like fluid from the firstcompartment through an opened first outlet solenoid valve. Because thevolume of the first and second compartments is known, controller 594 canprecisely meter fluid through the flowpaths by toggling the solenoidvalves of the balance chamber between the first compartment and thesecond compartment and control flow rate by controlling how often theinlet and outlet valves are cycled.

In an embodiment, device 500 includes a pH sensor 596 that ensures thepH of the cleansed salt solution is at or near 7.0 (i.e., neutral). ThepH sensor 596 may provide feedback to controller 594, so that controller594 controls pump 578 and/or valves 580, 582, 584, 586 to raise or lowerthe pH of the outflow as necessary. Device 500 may also include one ormore flowmeters (FM) 598 to monitor flow at any desired one or morelocation within the respective flowpaths of device 500 and provideflowrate feedback to controller 594.

FIG. 12 illustrates a device 600 that combines the urea decompositionand electrodialysis units discussed above into the same unit. Morespecifically, device 600 takes the electrodes from urea decompositionunit 50 and places the electrodes inside of multiple compartments ofelectrodialysis unit 300. The oxidation of urea from salt solutiontherefore occurs inside of the compartment due to the electrocatalyticsurfaces of the electrodes for decomposition of urea viaelectrooxidation. Device 600 may be used with any one, or more, or allof the controllers, valves, pH sensors, and/or flowmeters describedherein.

Similar to above, device 600 is a two-compartment, two-cellelectrodialysis unit including an anode 602 and a cathode 604 forseparation of a salt solution via electrodialysis. Device 600 includesan anode compartment 606 located between anode 602 and a first ionexchange membrane 618 and including an inlet 606 a and an outlet 606 b,a first compartment 608 located between first ion exchange membrane 618and a bipolar membrane 620 and including an inlet 608 a and an outlet608 b, a second compartment 610 located between bipolar membrane 620 anda second ion exchange membrane 622 and including an inlet 610 a and anoutlet 610 b, a third compartment 612 located between second ionexchange membrane 622 and a bipolar membrane 624 and including an inlet612 a and an outlet 612 b, a fourth compartment 614 located betweenbipolar membrane 624 and a third ion exchange membrane 626 and includingan inlet 614 a and an outlet 614 b, and a cathode compartment 616located between third ion exchange membrane 626 and cathode 604 andincluding an inlet 616 a and an outlet 616 b. In the illustratedembodiment, the first ion exchange membrane 618, second ion exchangemembrane 622 and third ion exchange membrane 626 are each a CEM.

First compartment 608 and third compartment 612 of device 600 eachinclude an electrooxidation cell 650 a, 650 b with one or more sets ofelectrodes with electrocatalytic surfaces for the decomposition of ureavia electrooxidation. As described above, each set of electrodes caninclude an anode and a cathode. In an embodiment, the electrodes includea cathode and an anode, and the anodes comprise a transition metaland/or mixtures thereof and/or alloys thereof. The transition metal canbe selected from the group consisting of cobalt, copper, iron, nickel,platinum, palladium, iridium, ruthenium, and rhodium. In an embodiment,the cathode can include platinum and the anode comprises wherein theanode comprises nickel, nickel oxide, nickel hydroxide or nickel oxidehydroxide (NiOOH). The electrooxidation cell 650 a, 650 b can alsoinclude an alkaline polymeric gel.

A power source (not shown) provides the electrodes of electrooxidationcells 650 a, 650 b with an electrical charge, and a power source 644 canbe used to create a potential difference between the anode 602 andcathode 604. Alternatively, the same power source can be used forelectrooxidation cells 650 a, 650 b and to create a potential differencebetween the anode 602 and cathode 604. The power source (not shown)provides the electrodes of electrooxidation cells 650 a, 650 b with anelectrical charge to activate an electrocatalytic surface of theelectrodes. The voltage difference applied across the electrodes (e.g.cathode and anode) can be sufficient to produce nitrogen gas, carbondioxide gas, and water. The power source 644 provides an electricalcharge to split water in bipolar membranes 620 and 624 into H⁺ and OH⁻.

Bipolar membranes 620 and 624 each include a CEM and an AEM as describedabove with respect to bipolar membrane 112. For each bipolar membrane620 and 624, water can be fed into a water compartment between the CEMand AEM from a source of water. For simplicity, the water compartment,CEM and AEM are not shown separately in FIG. 12. When a potentialdifference (e.g., a potential difference sufficient to split water) iscreated between the anode 602 and cathode 604, the potential differencecauses water to split into positively charged ions (H+) and negativelycharged ions (OH−). The generated negatively charged ions (OH−) frombipolar membrane 620 flow through the AEM and into first compartment608, and the generated positively charged ions (H+) flow through the CEMand into second compartment 610. Similarly, the potential differencecauses the negatively charged ions (OH−) from bipolar membrane 624 toflow through the AEM and into third compartment 612, and causes thepositively charged ions (H+) to flow through the CEM and into fourthcompartment 614.

FIG. 13 shows the flow paths of fluid through device 600. As shown byflowpaths 652, 654 and 656, salt solution (MX) from a source 651 can bepassed through anode compartment 606 and cathode compartment 616 andsent to drain 648 as described above. A salt solution can also be passedthrough each of first compartment 608 (flowpath 658), second compartment610 (flowpath 660), third compartment 612 (flowpath 662) and fourthcompartment 614 (flowpath 664). In the illustrated embodiment, first ionexchange membrane 618 is a first CEM 618, second ion exchange membrane622 is a second CEM 622, and third ion exchange membrane 626 is a thirdCEM 626. Salt solution (MX) passing through anode compartment 606therefore loses positively charged ions (M+) through CEM 618 to firstcompartment 608, salt solution passing through second compartment 610loses positively charged ions (M+) through CEM 622 to third compartment612, and salt solution passing through fourth compartment 614 losespositively charged ions (M+) through CEM 326 to cathode compartment 616.The AEM of bipolar membrane 620 prevents the positively charged ions(M+) from flowing out of first compartment 608, while the AEM of bipolarmembrane 624 prevents the positively charged ions (M+) from flowing outof third compartment 612. The potential difference created between anode602 and cathode 604 causes negatively charged ions (OH−) and positivelycharged ions (M+) to form a basic solution (MOH) with a high pH in firstcompartment 608 and third compartment 612.

The one or more sets (e.g., [set of electrodes]_(n), where n can be anyinteger) of electrodes with electrocatalytic surfaces ofelectrooxidation cell 650 a are located within first compartment 608because the salt solution (MX) within first compartment 608 becomes morebasic (alkaline) as positively charged ions (M+) from anode compartment606 combine with negatively charged ions (OH−) from bipolar membrane620. The one or more sets (e.g., [set of electrodes]_(n), where n can beany integer) of electrodes with electrocatalytic surfaces ofelectrooxidation cell 650 b are located within third compartment 612because the salt solution (MX) within third compartment 612 becomes morebasic (alkaline) as positively charged ions (M+) from second compartment610 combine with negatively charged ions (OH−) from bipolar membrane624. As explained above, it has been determined that a more basicalkaline solution is better for the decomposition of urea viaelectrooxidation. The urea cleansed salt solution from flowpaths 668 and670 can then be combined with the acidic solution from secondcompartment 610 and fourth compartment 614, as indicated by flowpaths672 and 674, respectively, to neutralize the overall pH of the combinedsolution output by device 600 at flowpath 676.

In use, first compartment 608 and third compartment 612 can receive muchmore solution than second compartment 610 and fourth compartment 614, sothat the majority of salt solution output at flowpath 676 is cleansed ofurea via electrooxidation. In an embodiment, the source of salt solution651 outputs about 405 mL/min of salt solution. 5 mL/min is directed toanode compartment 606 and cathode compartment 616 along flowpaths 652,654 and 656, 10 mL/min is directed to second compartment 610 alongflowpath 660, 10 mL/min is directed to fourth compartment 614 alongflowpath 664, and the other 380 mL/min is split between firstcompartment 608 and third compartment 612 along flowpaths 658 and 662,respectively (e.g., 190 mL/min along flowpath 658 and 190 mL/min alongflowpath 662). Thus, 94% of the salt solution leaving source 651, and95% of the cleansed solution leaving device 600 at flowpath 676, iscleansed of urea via electrooxidation.

FIG. 13 illustrates that in an embodiment, device 600 may include one ormore pump 678, and a plurality of valves 680, 682, 684, 686, 688 thatcontrol fluid flow along the respective flowpaths. Pump 678 may be aperistaltic pump or a volume membrane pump. The valves 680, 682, 684,686, 688 may be variable fluid orifice valves that allow a percentage offluid to flow through each respective flowpath. Alternatively, thevalves can be solenoid valves or other valves known to those of ordinaryskill in the art. In the illustrated embodiment, the valves 680, 682,684, 686, 688 are electrically connected to a controller 694. Thecontroller 694 may include one or more processor and memory programmedto control one or more pump 678 and the variable orifice size of valves680, 682, 684, 686, 688 to achieve the flow rates and percentagesdiscussed above or to achieve other flowrates and percentages throughthe respective flowpaths.

In an embodiment, any one or more or all of valves 680, 682, 684, 686,688 may alternatively be solenoid valves that operate with controller694 so that they are opened a specified amount of time to achieve theflow distributions through device 500 described above. In a furtherembodiment, one or more valves, such as valves 680, 682, 684, 686, 688,may be replaced with a balance chamber that operates with its ownvalves. Each balance chamber may include a first compartment and asecond compartment separated by a flexible membrane. When a first inletsolenoid valve opens to allow the first compartment to fill with fluid,the flexible membrane is pushed into the second compartment to expellike fluid from the second compartment through an opened second outletsolenoid valve. When a second inlet solenoid valve opens to allow thesecond compartment to fill with fluid, the flexible membrane is pushedinto the first compartment to expel like fluid from the firstcompartment through an opened first outlet solenoid valve. Because thevolume of the first and second compartments is known, controller 494 canprecisely meter fluid through the flowpaths by toggling the solenoidvalves of the balance chamber between the first compartment and thesecond compartment and control flow rate by controlling how often theinlet and outlet valves are cycled.

In an embodiment, device 600 includes a pH sensor 696 that ensures thepH of the cleansed salt solution is at or near 7.0 (i.e., neutral). ThepH sensor 696 may provide feedback to controller 694, so that controller694 controls pump 678 and/or valves 680, 682, 684, 686, 688 to raise orlower the pH of the outflow as necessary. Device 600 may also includeone or more flowmeters (FM) 698 to monitor flow at any desired one ormore location within the respective flowpaths of device 600 and provideflowrate feedback to controller 694.

FIG. 14 illustrates an embodiment of a device 20 for the removal of ureafrom a fluid having urea to produce a cleansed fluid. In the illustratedembodiment, device 20 includes a urea decomposition unit 50 and anelectrodialysis unit 100, 200, 300 as described above. Device 20 furtherincludes a source of dialysis solution 22, a basic tank 24, an acid tank26 and a dialysis fluid equalization unit 28. Device 20 may also employany one or more of the controllers, one or more pump, valves, pHsensors, and/or flowmeters described herein.

In the illustrated embodiment, salt solution containing urea firstpasses from the source of dialysis fluid solution 22 to either of (i)urea decomposition unit 50 to be oxidized or (ii) electrodialysis unit100, 200, 300 to be separated into an acidic solution and a basicsolution. As illustrated, dialysis fluid solution first passes to valve32 via flowpath 30. Valve 32 can then direct the dialysis solution tourea decomposition unit 50 via flowpath 34, valve 36 and flowpath 38, orvalve 32 can direct the dialysis solution to electrodialysis unit 100,200, 300 via flowpath 40.

Electrodialysis unit 100, 200, 300 separates the dialysis fluid solutioninto a basic solution and an acid solution as described above. The basicsolution flows out of electrodialysis unit 100, 200, 300 at flowpath 42.The acidic solution flows out of electrodialysis unit 100, 200, 300 atflowpath 44.

Valve 46 can either (i) direct the basic solution to flowpath 48 to bestored in basic tank 24, (i) direct the basic solution to flowpaths 52and 38 to be mixed with original dialysis fluid from source 22 beforethe original dialysis fluid is directed to urea decomposition unit 50,or (iii) direct the basic solution to flowpath 54 to mix with dialysisfluid solution that has exited urea decomposition unit 50. Valve 46 cantherefore be used to precisely control the pH of fluid entering orleaving urea decomposition unit 50. If the solution entering or leavingurea decomposition unit 50 needs the pH raised more than what can beprovided by the basic solution flowing out of flowpath 42, valve 46allows additional basic solution to be pulled from basic solution tank24 along flowpath 48.

Acid tank 26 receives acidic solution from electrodialysis unit 100,200, 300. The acidic solution can then be flowed to valve 58 viaflowpath 56. Valve 58 can either (i) direct the acidic solution viaflowpath 60 to be mixed with oxidized solution leaving ureadecomposition unit 50 to lower the pH of the oxidized solution leavingurea decomposition unit 50, or (ii) direct the acidic solution back tovalve 32 via flowpath 62, so that the acidic solution can then bedirected through one or more of the flowpaths and components of device20 after treatment to clean the flowpaths and components. It should beunderstood from FIG. 10 that the acidic solution can be directed throughany of the valves and flowpaths and any of urea decomposition unit 50,electrodialysis unit 100, 200, 300, basic tank 24, acid tank 26 anddialysis fluid equalization unit 28, in order to clean these valves,flowpaths and other components.

Dialysis fluid equalization unit 28 can be used to neutralize thedialysis fluid that has been cleaned of urea by urea decomposition unit50. In an embodiment, the pH of dialysis fluid exiting ureadecomposition unit 50 is measured at dialysis fluid equalization unit28. If the measured pH is too high, dialysis fluid equalization unit 28receives additional acidic solution from acid tank 26, via flowpaths 56,60 and 64, so that the pH can be lowered to an acceptable level. If themeasured pH is too low, dialysis fluid equalization unit 28 receivesadditional basic solution from basic tank 24, via flowpaths 48, 54 and64, so that the pH can be raised to an acceptable level. Dialysis fluidequalization unit 28 can continue to measure the pH of the dialysisfluid solution therein and receive acidic and basic solution until thedialysis fluid solution therein is safe for treatment. In an alternativeembodiment, the pH of solution leaving urea decomposition unit 50 can bebalanced and immediately used for renal failure therapy.

The methods of the present disclosure preferably remove a substantialamount of urea from a solution containing urea including, for example,10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of the urea.

During operation of the disclosed devices, Ca2+ and Mg2+ may be depletedin urea decomposition unit 50 and electrodialysis unit 100, 200, 300.Without wishing to be bound by a theory of the invention, it is believedthat Ca2+ and Mg2+ become depleted during operation of the discloseddevices due to hydroxide formation and precipitation. To remove calciumand magnesium precipitates, the acidic solution stored in the acid tankis circulated through the urea decomposition unit 50 and electrodialysisunit 100, 200, 300. The acid solution solubilizes the calcium andmagnesium precipitates and thus prevents membrane and electrode foulingwhile restoring Ca2+ and Mg2+ to the cleansed salt solution. In anembodiment, the devices disclosed herein can include a centralcontroller than controls all of the pumps and valves, as well as theflowrates through the flowpaths. It should be understood that the arrowsshown in the figures herein represent flowpaths, and that one or morepumps can be included along any of the flowpaths disclosed herein topump fluid through the flowpaths. Valves can also be positioned anywherealong any of the flowpaths for the same purpose. By controlling thepumps and valves, central controller can control the flowrates throughthe flowpaths and the pH of the anywhere in the system. It should beunderstood from the present disclosure that any of the devices describedabove can be included in a dialysis fluid circuit of a renal replacementtherapy system. In an embodiment, the sources of salt solution discussedabove can be sources of used/used dialysis fluid from the renalreplacement therapy system. In an embodiment, the cleansed salt solutionillustrated in the Figures herein can be regenerated dialysis fluid thatcan be reused by the renal replacement therapy system for treatment of apatient. The salt solution discussed herein can be any type of dialysisfluid/renal therapy solution containing urea. In an embodiment, therenal replacement therapy system can be a hemodialysis system, aperitoneal dialysis system, a hemofiltration system or ahemodiafiltration system.

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as molecular weight, reaction conditions,and so forth used in the specification and claims are to be understoodas being modified in all instances by the term “about.” Accordingly,unless indicated to the contrary, the numerical parameters set forth inthe specification and attached claims are approximations that may varydepending upon the desired properties sought to be obtained by thepresent disclosure. At the very least, and not as an attempt to limitthe application of the doctrine of equivalents to the scope of theclaims, each numerical parameter should at least be construed in lightof the number of reported significant digits and by applying ordinaryrounding techniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the disclosure are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

The terms “a,” “an,” “the” and similar referents used in the context ofdescribing the disclosure (especially in the context of the followingclaims) are to be construed to cover both the singular and the plural,unless otherwise indicated herein or clearly contradicted by context.Recitation of ranges of values herein is merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range. Unless otherwise indicated herein, eachindividual value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein isintended merely to better illuminate the disclosure and does not pose alimitation on the scope of the disclosure otherwise claimed. No languagein the specification should be construed as indicating any non-claimedelement essential to the practice of the disclosure.

Groupings of alternative elements or embodiments of the disclosuredisclosed herein are not to be construed as limitations. Each groupmember can be referred to and claimed individually or in any combinationwith other members of the group or other elements found herein. It isanticipated that one or more members of a group can be included in, ordeleted from, a group for reasons of convenience and/or patentability.When any such inclusion or deletion occurs, the specification is deemedto contain the group as modified thus fulfilling the written descriptionof all Markush groups used in the appended claims.

Certain embodiments of this disclosure are described herein, includingthe best mode known to the inventors for carrying out the disclosure. Ofcourse, variations on these described embodiments will become apparentto those of ordinary skill in the art upon reading the foregoingdescription. The inventor expects skilled artisans to employ suchvariations as appropriate, and the inventors intend for the disclosureto be practiced otherwise than specifically described herein.Accordingly, this disclosure includes all modifications and equivalentsof the subject matter recited in the claims appended hereto as permittedby applicable law. Moreover, any combination of the above-describedelements in all possible variations thereof is encompassed by thedisclosure unless otherwise indicated herein or otherwise clearlycontradicted by context.

Specific embodiments disclosed herein can be further limited in theclaims using consisting of or and consisting essentially of language.When used in the claims, whether as filed or added per amendment, thetransition term “consisting of” excludes any element, step, oringredient not specified in the claims. The transition term “consistingessentially of” limits the scope of a claim to the specified materialsor steps and those that do not materially affect the basic and novelcharacteristic(s). Embodiments of the disclosure so claimed areinherently or expressly described and enabled herein.

It is to be understood that the embodiments of the disclosure disclosedherein are illustrative of the principles of the present disclosure.Other modifications that can be employed are within the scope of thedisclosure. Thus, by way of example, but not of limitation, alternativeconfigurations of the present disclosure can be utilized in accordancewith the teachings herein. Accordingly, the present disclosure is notlimited to that precisely as shown and described.

While the present disclosure has been described and illustrated hereinby references to various specific materials, procedures and examples, itis understood that the disclosure is not restricted to the particularcombinations of materials and procedures selected for that purpose.Numerous variations of such details can be implied as will beappreciated by those skilled in the art. It is intended that thespecification and examples be considered as exemplary, only, with thetrue scope and spirit of the disclosure being indicated by the followingclaims. All references, patents, and patent applications referred to inthis application are herein incorporated by reference in their entirety.

1. A device for the removal of urea from a fluid having urea to producea cleansed fluid, the device comprising: a urea decomposition unitcomprising an inlet for entry of the fluid having urea and an outlet forremoval of the cleansed fluid, and one or more sets of electrodes havingan anode and a cathode with an electrocatalytic surface fordecomposition of urea via electrooxidation; and an electrodialysis unitcomprising a set of electrodes having an anode and a cathode forseparation of a salt solution via electrodialysis, where the saltsolution is separated into an acid stream and a basic stream, wherein atleast one of (i) the basic stream of the electrodialysis unit is placedin fluid communication with the inlet of the urea decomposition unit,(ii) the acid stream from the electrodialysis unit is placed in fluidcommunication with the outlet of the urea decomposition unit, or (iii)the acid stream is circulated through the electrodialysis unit.
 2. Thedevice of claim 1, wherein the electrodialysis unit comprises a firstcell comprising a first bipolar membrane, a first ion exchange membrane,and a second ion exchange membrane, wherein the first ion exchangemembrane is positioned next to one side of the first bipolar membraneand the second ion exchange membrane is positioned next to an oppositeside of the first bipolar membrane, thereby forming (i) a firstcompartment between the first bipolar membrane and the first ionexchange membrane and (ii) a second compartment between the firstbipolar membrane and the second ion exchange membrane.
 3. The device ofclaim 2, wherein the first ion exchange membrane is an anion exchangemembrane or a cation exchange membrane.
 4. The device of claim 2,wherein the second ion exchange membrane is an anion exchange membraneor a cation exchange membrane.
 5. The device of claim 2, wherein theelectrodialysis unit further comprises a second cell including a secondbipolar membrane and a third ion exchange membrane, wherein the secondcell is positioned next to the first cell, and wherein the secondbipolar membrane is positioned between the second ion exchange membraneof the first cell and the third ion exchange membrane, thereby forming athird compartment between the second bipolar membrane and the third ionexchange membrane.
 6. The device of claim 5, wherein the first, second,and third ion exchange membranes are cation exchange membranes, orwherein the first, second, and third ion exchange membranes are anionexchange membranes.
 7. The device of claim 1, wherein theelectrodialysis unit comprises a cell including a first bipolarmembrane, a second bipolar membrane, a first ion exchange membrane, anda second ion exchange membrane, wherein the first ion exchange membraneand the second ion exchange membrane are positioned between the firstbipolar membrane and the second bipolar membrane, thereby forming afirst compartment between the first bipolar membrane and the first ionexchange membrane, a second compartment between the first ion exchangemembrane and the second ion exchange membrane, and a third compartmentbetween the second ion exchange membrane and the second bipolarmembrane.
 8. The device of claim 7, wherein the first ion exchangemembrane is a cation exchange membrane and the second ion exchangemembrane is an anion exchange membrane.
 9. The device of claim 1,wherein a power source in the urea decomposition unit provides theelectrodes with an electrical charge to activate the electrocatalyticsurface of the electrodes.
 10. The device of claim 1, wherein a powersource in the electrodialysis unit provides the electrodes with anelectrical charge to split water in a bipolar membrane into H⁺ and OH⁻.11. The device of claim 1, wherein the electrodialysis unit separatesthe salt solution via bipolar membrane electrodialysis.
 12. The deviceof claim 1, wherein the basic stream of the electrodialysis unit is influid communication with the inlet of the urea decomposition unit andthe acid stream from the electrodialysis unit is in fluid communicationwith the outlet of the urea decomposition unit.
 13. The device of claim1, wherein the salt solution is a dialysis fluid.
 14. The device ofclaim 13, wherein the dialysis fluid includes one or more salts selectedfrom the group consisting of: a sodium salt, a magnesium salt, a calciumsalt, lactate, carbonate, acetate, citrate, or phosphate.
 15. The deviceof claim 1 further comprising a tank for the salt solution.
 16. Thedevice of claim 1, wherein the basic stream includes NaOH.
 17. Thedevice of claim 1, wherein the acid stream includes HCl.
 18. The deviceof claim 1, wherein the anodes in the urea decomposition unit comprise atransition metal and/or mixtures thereof and/or alloys thereof.
 19. Thedevice of claim 18, wherein the transition metal is cobalt, copper,iron, nickel, platinum, palladium, iridium, ruthenium, or rhodium. 20.The device of claim 18, wherein the anodes in the urea decompositionunit comprise nickel, nickel oxide, nickel hydroxide or nickel oxidehydroxide (NiOOH).
 21. The device of claim 1, wherein the ureadecomposition unit includes an alkaline polymeric gel.
 22. The device ofclaim 1, wherein the fluid having urea is a dialysis fluid contaminatedwith urea.
 23. The device of claim 1, wherein a voltage differenceapplied across the cathodes and the anodes in the urea decompositionunit is sufficient to produce nitrogen gas, carbon dioxide gas, andwater.
 24. A renal replacement therapy system comprising: a dialysisfluid circuit, wherein the dialysis fluid circuit comprises a device forthe removal of urea from a dialysis fluid having urea to produce acleansed dialysis fluid, the device comprising: a urea decompositionunit comprising an inlet for entry of the dialysis fluid having urea andan outlet for removal of the cleansed dialysis fluid, and a set ofelectrodes having an anode and a cathode with an electrocatalyticsurface for decomposition of urea via electrooxidation; and anelectrodialysis unit comprising a set of electrodes having an anode anda cathode for separation of a salt solution via electrodialysis, wherethe salt solution is separated into an acid stream and a basic stream,wherein at least one of (i) the basic stream of the electrodialysis unitis placed in fluid communication with the inlet of the ureadecomposition unit, (ii) the acid stream from the electrodialysis unitis placed in fluid communication with the outlet of the ureadecomposition unit, or (iii) the acid stream is circulated through theelectrodialysis unit.
 25. The renal replacement therapy system of claim24, wherein the cleansed dialysis fluid recirculates through thedialysis fluid circuit.
 26. The renal replacement therapy system ofclaim 24, wherein the electrodialysis unit comprises a first cellincluding a first bipolar membrane, a first ion exchange membrane, and asecond ion exchange membrane, wherein the first ion exchange membrane ispositioned next to one side of the first bipolar membrane and the secondion exchange membrane is positioned next to an opposite side of thefirst bipolar membrane, thereby forming a first compartment between thefirst bipolar membrane and the first ion exchange membrane and a secondcompartment between the first bipolar membrane and the second ionexchange membrane.
 27. The renal replacement therapy system of claim 26,wherein the first ion exchange membrane is an anion exchange membrane ora cation exchange membrane.
 28. The renal replacement therapy system ofclaim 26, wherein the second ion exchange membrane is an anion exchangemembrane or a cation exchange membrane.
 29. The renal replacementtherapy system of claim 26, wherein the electrodialysis unit furthercomprises a second cell including a second bipolar membrane and a thirdion exchange membrane, wherein the second cell is positioned next to thefirst cell, and wherein the second bipolar membrane is positionedbetween the second ion exchange membrane of the first cell and the thirdion exchange membrane, thereby forming a third compartment between thesecond bipolar membrane and the third ion exchange membrane.
 30. Therenal replacement therapy system of claim 29, wherein the first, second,and third ion exchange membranes are cation exchange membranes orwherein the first, second, and third ion exchange membranes are anionexchange membranes.
 31. The renal replacement therapy system of claim24, wherein the electrodialysis unit comprises a cell including a firstbipolar membrane, a second bipolar membrane, a first ion exchangemembrane, and a second ion exchange membrane, wherein the first ionexchange membrane and the second ion exchange membrane are positionedbetween the first bipolar membrane and the second bipolar membrane,thereby forming a first compartment between the first bipolar membraneand the first ion exchange membrane, a second compartment between thefirst ion exchange membrane and the second ion exchange membrane, and athird compartment between the second ion exchange membrane and thesecond bipolar membrane.
 32. The renal replacement therapy system ofclaim 31, wherein the first ion exchange membrane is a cation exchangemembrane and the second ion exchange membrane is an anion exchangemembrane.
 33. The renal replacement therapy system of claim 24, whereina power source in the urea decomposition unit provides the electrodeswith an electrical charge to activate the electrocatalytic surface ofthe electrodes.
 34. The renal replacement therapy system of claim 24,wherein a power source in the electrodialysis unit provides theelectrodes with an electrical charge to split water in a bipolarmembrane into H⁺ and OH⁻.
 35. The renal replacement therapy system ofclaim 24, wherein the electrodialysis unit separates the salt solutionvia bipolar membrane electrodialysis.
 36. The renal replacement therapysystem of claim 24, wherein the salt solution is a dialysis fluid. 37.The renal replacement therapy system of claim 36, wherein the dialysisfluid includes one or more salts selected from the group consisting of:a sodium salt, a magnesium salt, a calcium salt, lactate, carbonate,acetate, citrate, or phosphate.
 38. The renal replacement therapy systemof claim 24, further comprising a tank for the salt solution.
 39. Therenal replacement therapy system of claim 24, wherein the basic streamincludes NaOH.
 40. The renal replacement therapy system of claim 24,wherein the acid stream includes HCl.
 41. The renal replacement therapysystem of claim 24, wherein the anodes in the urea decomposition unitcomprise a transition metal and/or mixtures thereof and/or alloysthereof.
 42. The renal replacement therapy system of claim 41, whereinthe transition metal is cobalt, copper, iron, nickel, platinum,palladium, iridium, ruthenium, or rhodium.
 43. The renal replacementtherapy system of claim 41, wherein the anodes in the urea decompositionunit comprise nickel, nickel oxide, nickel hydroxide or nickel oxidehydroxide (NiOOH).
 44. The renal replacement therapy system of claim 24,wherein the urea decomposition unit includes an alkaline polymeric gel.45. The renal replacement therapy system of claim 24, wherein a voltagedifference applied across the cathodes and the anodes in the ureadecomposition unit is sufficient to produce nitrogen gas, carbon dioxidegas, and water.
 46. A method of cleaning a used dialysis fluid havingurea to produce a cleansed dialysis fluid, the method comprising:passing a used dialysis fluid having urea through a device comprising: aurea decomposition unit comprising an inlet for entry of the useddialysis fluid having urea and an outlet for removal of the cleanseddialysis fluid, and a set of electrodes having an anode and a cathodewith an electrocatalytic surface for decomposition of urea viaelectrooxidation; and an electrodialysis unit comprising a set ofelectrodes having an anode and a cathode with an electrocatalyticsurface for separation of a salt solution via electrodialysis, where thesalt solution is separated into an acid stream and a basic stream,wherein at least one of (i) the basic stream of the electrodialysis unitis placed in fluid communication with the inlet of the ureadecomposition unit, (ii) the acid stream from the electrodialysis unitis in fluid communication with the outlet of the urea decompositionunit, or (iii) the acid stream is circulated through the electrodialysisunit, and wherein the dialysis fluid exiting the outlet of the ureadecomposition unit is cleansed dialysis fluid.
 47. The method of claim46, wherein the electrodialysis unit comprises a first cell including afirst bipolar membrane, a first ion exchange membrane, and a second ionexchange membrane, wherein the first ion exchange membrane is positionednext to one side of the first bipolar membrane and the second ionexchange membrane is positioned next to an opposite side of the firstbipolar membrane, thereby forming a first compartment between the firstbipolar membrane and the first ion exchange membrane and a secondcompartment between the first bipolar membrane and the second ionexchange membrane.
 48. The method of claim 47, wherein the first ionexchange membrane is an anion exchange membrane or a cation exchangemembrane.
 49. The method of claim 47, wherein the second ion exchangemembrane is an anion exchange membrane or a cation exchange membrane.50. The method of claim 47, wherein the electrodialysis unit furthercomprises a second cell including a second bipolar membrane and a thirdion exchange membrane, wherein the second cell is positioned next to thefirst cell, and wherein the second bipolar membrane is positionedbetween the second ion exchange membrane of the first cell and the thirdion exchange membrane, thereby forming a third compartment between thesecond bipolar membrane and the third ion exchange membrane.
 51. Themethod of claim 50, wherein the first, second, and third ion exchangemembranes are cation exchange membranes or wherein the first, second,and third ion exchange membranes are anion exchange membranes.
 52. Themethod of claim 46, wherein the electrodialysis unit comprises a cellincluding a first bipolar membrane, a second bipolar membrane, a firstion exchange membrane, and a second ion exchange membrane, wherein thefirst ion exchange membrane and the second ion exchange membrane arepositioned between the first bipolar membrane and the second bipolarmembrane, thereby forming a first compartment between the first bipolarmembrane and the first ion exchange membrane, a second compartmentbetween the first ion exchange membrane and the second ion exchangemembrane, and a third compartment between the second ion exchangemembrane and the second bipolar membrane.
 53. The method of claim 52,wherein the first ion exchange membrane is a cation exchange membraneand the second ion exchange membrane is an anion exchange membrane. 54.The method of claim 46, wherein a power source in the urea decompositionunit provides the electrodes with an electrical charge to activate theelectrocatalytic surface of the electrodes.
 55. The method of claim 46,wherein a power source in the electrodialysis unit provides theelectrodes with an electrical charge to split water in a bipolarmembrane into H⁺ and OH⁻.
 56. The method of claim 46, wherein theelectrodialysis unit separates the salt solution via bipolar membraneelectrodialysis.
 57. The method of claim 46, wherein the salt solutionis a dialysis fluid.
 58. The method of claim 57, wherein the dialysisfluid includes one or more salts selected from the group consisting of:a sodium salt, a magnesium salt, a calcium salt, lactate, carbonate,acetate, citrate, or phosphate.
 59. The method of claim 46, furthercomprising a tank for the salt solution.
 60. The method of claim 46,wherein the basic stream includes NaOH.
 61. The method of claim 46,wherein the acid stream includes HCl.
 62. The method of claim 46,wherein the anodes in the urea decomposition unit comprise a transitionmetal and/or mixtures thereof and/or alloys thereof.
 63. The method ofclaim 62, wherein the transition metal is cobalt, copper, iron, nickel,platinum, palladium, iridium, ruthenium, or rhodium.
 64. The method ofclaim 62, wherein the anodes in the urea decomposition unit comprisenickel, nickel oxide, nickel hydroxide or nickel oxide hydroxide(NiOOH).
 65. The method of claim 46, wherein the urea decomposition unitincludes an alkaline polymeric gel.
 66. The method of claim 46, whereina voltage difference applied across the cathodes and the anodes in theurea decomposition unit is sufficient to produce nitrogen gas, carbondioxide gas, and water.